Computer studies analysis of questions and answers

Compute the value of x in the following expressions

11/6/2023

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Compute the value of x in the following expressions

(i) 24.3510 = X₂ (3mks)

(ii) 6ABH = X₁₀ (2mks)

Using twos complements compute the following using 8 bits binary (4mks)

25₁₀ – 20₁₀

c) Subtract the following binary numbers using the One’s Compliment method. (3mks)

(11101)₂ – (1010)₂

d)Convert 6057₈ to Hexadecimal. (3mks)

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List four areas that would be considered in the requirement specification.

18/11/2021

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(a) List and describe four strategies for converting from an old system to a new system. (4mks)

Direct approach
user simply stops using old system and starts using the new one
Parallel approach
old and new system are operated side by side until the new system has shown it is reliable
Phased approach
parts of a new system are phased in separately either at different times or all at one in groups
Pilot approach
entire system is tried out but only by some users

(b) (i) Distinguish between private data and confidential data (2mks)

Private data
belongs to an individual and must be accessed through direct permission from the owner
Confidential data
held by government or organization about people but can be seen by authorized people only.

(ii) What can be done to stop illegal access to a computer laboratory by unauthorized people (3mks)

fit strong metallic grills and locks to doors
don’t welcome strangers into the lab
install alarms
employ guards
burglar proof

(c) (i) List four areas that would be considered in the requirement specification. (4mks)

output specification
in put specification
file /data/tables
hard ware/soft ware

(ii) Name any two areas covered in feasibility report during system analysis and design. (2mks)

Lost benefit analyst
Schedule
Users
Environment
Technology

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The information below is maintained by the sales lady at the school canteen. Study it and answer the questions that follow.

17/11/2021

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The information below is maintained by the sales lady at the school canteen. Study it and answer the questions that follow.

(a) Describe the basic data types used in this spreadsheet (4mks)

Labels
describing items names
Values
describing units on column B and C

(b) Provide a single formula that would be used to
(i) Count the number of items whose units are equal; to 15 (2mks)

=COUNTIF(B2:B5,15) or =COUNTIF(B2:B5,=15)

(ii) Sum the values of items whole units are equal to 12 (2mks)

=SUMIF(B2:B5,"=12") or =SUMIF(B2:B5,"12")

(c) (i) List and describe four areas of application of spreadsheets (4mks)

Accounting
What IF analysis (forecasting)
Budgeting
Calendars
Expense reports
Forms
Time sheets
Invoices
Purchase Orders
Receipts
Schedules

(ii) Explain data range legend and axis as used in spreadsheet charts (3mks)

Axis

A reference line from \which distances or angles are measured in a coordinate system, such as the X-axis and y-axis in the Cartesian coordinate system

Legend

Brief description accompanying an illustration (chart) also known as a caption

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List three advantages and three disadvantages of fibre optic cable and Name two types of coaxial cables

17/11/2021

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(a) List three advantages and three disadvantages of fibre optic cable (6mks)
Advantages

immune to electro magnetic interference and ear dropping
fast and supports high band width
large distance can be covered because it has low attenuation
can be used in hazardous environment
smaller and lighter than copper

Disadvantages

connecting devices are expensive
installation is difficult
complex to configure
expensive/ difficult to repair

(b) Describe the following signals and state where each is applied in network communication. (4mks)
Analog

made up of continuous varied wave form.
it is transmitted over telephone line.
a codec converts an analog signal to digital for transmission via a digital medium

Digital

made up of non continuous discrete wave form computers
a modem converts a digital signal to analog for transmission over the analog media

(c) Name two types of coaxial cables (2mks)

thin net
thick net

(d) (i) Distinguish between microwave and satellite transmissions. (2mks)

Microwave transmission consists of point to point transmissions meaning a signal is divided through a focused beam from transmitter to receiver while satellite is usually launched into speck

(ii) Give an example of internet protocol (1mk)

ICPIP [Internet Control Message Protocol]
TCP [Transmission Control Protocol]
IP [Internet Protocol]

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Describe three methods you would use in error detection during program testing

16/11/2021

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(a)When invoicing customers, the invoice clerk has to work out the discounts allowable on each order. Any order over 20,000/= attracts a “bulk” discount of 7%. A customer within the trade is allowed 10%. There is also a special discount of 2% allowed for any customer who has been ordering regularly for over 2 years. Using a flowchart show clerical procedure for working out discount entitlement.

When invoicing customers, the invoice clerk has to work out the discounts allowable on each order. Any order over 20,000/= attracts a “bulk” discount of 7%. A customer within the trade is allowed 10%. There is also a special discount of 2% allowed for any customer who has been ordering regularly for over 2 years. Using a flowchart show clerical procedure for working out discount entitlement.

(b) Name the control structures you have used in the flow chart (2mks)

selection
sequence

Describe three methods you would use in error detection during program testing

error detection methods

desk checking (dry-run)
going through the program while still on paper
using debugging utilities
enter the program editor where syntax errors are detected during translation
using test date
carries out trial runs
various data variations and extreme including good and bad data are entered to see how the program would handle them

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A school has been advised to employ a database administrator. State three responsibilities of this personnel in the school.

15/1/2021

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A school has been advised to employ a database administrator. State three responsibilities of this personnel in the school.

(b) Explain two ways in which computers can be used in the transport industry.
(c) Mary was advised to partition a hard disk for her computer. Explain two reasons that may have necessitated this.
(d) Explain a reason for conducting each of the following studies in systems development:
(i) Schedule feasibility;
(ii) Technical feasibility.

RESPONSES

a) Possible responsibilities of a database admin in a school

Carrying out school database backups.
Recovering of lost school data incase of system failure.
Ensuring the security and integrity of the school system.
Adding new users to the school system and managing the user’s accounts.
Designing and developing database application for the school.
Updating or maintaining database for the school.

b) Ways in which computers can be used in a transport industry.

Use of GPS to track vehicles, flights etc.
Bookings to different destinations can be done through the use of computers ( online booking).
The computers can also be used to reduce the speed of vehicles and bring sanity in the industry.
Managing human resource involved in the industry.

c) Reasons for partitioning hard disk

For security purposes, incase one partition fails the second partition remains functional.
If she requires backup copies to be stored in the same hard disk.
If she intends to install more than one operating system.

d) (I Schedule feasibility

To determine if the proposed solution can be developed within the required time.

(ii) Technical feasibility

To determine if the system can be supported by the available technology.

(b) Explain two ways in which computers can be used in the transport industry. (c) Mary was advised to partition a hard disk for her computer. Explain two reasons that may have necessitated this. (d) Explain a reason for conducting each of the following studies in systems development: (i) Schedule feasibility; (ii) Technical feasibility.

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Distinguish between a microwave transmission and a radio transmission.

15/1/2021

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Distinguish between a microwave transmission and a radio transmission.

(b) Figure 1 shows a computer, network topology. Use it to answer the questions that follow.

(i)Identify the type of topology.
(ii) State the function of each of the parts labelled A and B.
(c) A computer laboratory experiences power supply problems. Describe three power related problems that should be addressed.

RESPONSES

b) (i) Bus topology
(ii) A - The Bus cable

It is a core section of the bus topology network which has all the nodes connected to it and data pass through it.

B — Terminator

It destroys data that does not reach its destination so that it doesn’t cause echo back.

c) Problems related to power that should be addressed

Blackout: This is unexpected discontinuation of power supply in the laboratory.
Power sage: Sudden drop of voltage levels that lasts less than a second.
Transients! surge: High voltage flowing.
Brownout: Partial blackout where there’s low voltage flow.
Short circuit: live wires touching each other’s
Loose connection, which may cause tripping or total power failure

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Describe three arithmetic errors that may occur during computerised data processing.

15/1/2021

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Describe three arithmetic errors that may occur during computerised data processing.

(b) Arnold a programmer intends to create a user input interface screen for a system. State three factors that he should consider.
(c)With the aid of an example in each case describe the following types of maintenance.
(i) adaptive;
(ii) perfective;
(iii) corrective.

RESPONSES

a) Arithmetic errors
Truncation error

Results due, to shortening or leaving out part of a number or a word.
Rounding off error
Arising by approximating a number by replacing it with a number that has fewer significant digits or one with zeros for its ending digits.

Overflow error

Occurs when the results of a computation is larger than the allocated memory space.

Underflow error

Type of error occurs when the output is low small to be represented in the chosen format.

b) User interface design considerations

Should be user friendly.
Colour, fonts and layout should be appealing to the user.
Consider a consistent layout in the entire system.
Should prompt user clearly.
Should capture the same number of items of date as indicated in the manual data capture form.

(c)Types of maintenance
(i) Adaptive

Type of maintenance that is done to make the system to adopt the changing technology e.g. changing the system because to new ois

(ii) Perfective

Type of maintenance done to make the system better in its operation e.g. adding a module in a system.

(iii) Corrective

Type of maintenance done to correct an error in the system e.g.wrong results during addition.

a) Arithmetic errors Truncation error Results due, to shortening or leaving out part of a number or a word. Rounding off error Arising by approximating a number by replacing it with a number that has fewer significant digits or one with zeros for its ending digits. Overflow error Occurs when the results of a computation is larger than the allocated memory space. Underflow error Type of error occurs when the output is low small to be represented in the chosen format. b) User interface design considerations Should be user friendly. Colour, fonts and layout should be appealing to the user. Consider a consistent layout in the entire system. Should prompt user clearly. Should capture the same number of items of date as indicated in the manual data capture form. (c)Types of maintenance (i) Adaptive Type of maintenance that is done to make the system to adopt the changing technology e.g. changing the system because to new ois (ii) Perfective Type of maintenance done to make the system better in its operation e.g. adding a module in a system. (iii) Corrective Type of maintenance done to correct an error in the system e.g.wrong results during addition.

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State two qualities of a good pseudocode.

15/1/2021

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State two qualities of a good pseudocode.

should be short and clean precise
should have start and end clearly shown.
Statements should be clearly defined.
should depict the logical flow of solving the problem.
should not be ambiguous.
it should be indented /neat / legibility

(b) With the aid of flowchart diagrams, describe each of the following programme control structures:
(i) sequence
(ii) selection

(i)Sequence

Program statements are executed one after the other in the order in which they appear.

(ii) Selection

(c) Draw a programme flowchart that would accept three numbers and find their sum. If the sum is greater than 200. It adds 30 to the sum, otherwise subtracts 20 from the sum. The programme should then display the results.

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Explain three ways in which an operating system provides data security in a computer system

14/1/2021

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Explain three ways in which an operating system provides data security in a computer system

Access control:

Deals with the problem of verifying /authenticating the identity of a user before permitting access to the request resource (e.g. use of passwords, user account);

Encryption

Transforming data into an unreadable format so that they are safely transmitted;

Firewalls

Filters out unwanted data and programs/criminals/hackers/malicoius persons;

Log files

A means by which transactions in a computer system can be recorded thereby detering potential infiltrators;
Alerts
Alerting a user when he/she is about to delete a file/folder.

(b)State two instances where observation is not a viable method of gathering data during system analysis stage.

When the analyst wants to collect confidential information,
When there is a large group of people involved in the system,
Where the people you want to gather information from are vastly dispersed

A device used to re-construct data signal during data transmission to its original strength/amplify/boost/regenerate.

II. router.

It is a device used to facilitate movement of data or packets between two or more LANS of different configuration (expansion of networks).
Delivers a packet/data directly to destination computers.
Interconnects different networks/provides network services.

(ii) The figure below shows a network based on the bus topology.

(b)State two instances where observation is not a viable method of gathering data during system analysis stage. When the analyst wants to collect confidential information, When there is a large group of people involved in the system, Where the people you want to gather information from are vastly dispersed (c) (i) State the role of each of the following data communication devices: I. repeater A device used to re-construct data signal during data transmission to its original strength/amplify/boost/regenerate. II. router. It is a device used to facilitate movement of data or packets between two or more LANS of different configuration (expansion of networks). Delivers a packet/data directly to destination computers. Interconnects different networks/provides network services. (ii) The figure below shows a network based on the bus topology.

I. Identify the component labelled P.

The component P is the terminator.

II. State the function of the component labelled P.

Terminator in a backbone is used to prevent data signal from bouncing back/absorb signals.

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Figure 2 shows a block diagram of a computer system and its peripheral devices. Use it and answer the questions that follow.

14/1/2021

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Explain two health issues that could arise from the use of unsuitable computer desk.

No.19.(a) Figure 2 shows a block diagram of a computer system and its peripheral devices. Use it and answer the questions that follow. (i)Name two devices that may be used for storing data for a long duration. 2GB HDD 32 MB Rom (ii) Name three peripheral devices that are used for input. Mouse Scanner CD drive (iii)Name two other devices that a Computer Aided Design (CAD) user might wish to add to the set up above in order to perform his tasks effectively. Digitizer Keyboard USB port 19 (b) A customer wishes to purchase a computer system. The customer can buy word processor, spreadsheet, database, and a drawing package separately or as an integrated package. State three reasons why the customer would prefer an integrated package to separate packages The software provides easy movement of data among the separate applications, A common group of commands is used for all the applications in the software package, Provides easy switching between functions without having to go back to the operating system and ability to share data between functions.

(i)Name two devices that may be used for storing data for a long duration.

2GB HDD
32 MB Rom

(ii) Name three peripheral devices that are used for input.

Mouse
Scanner
CD drive

(iii)Name two other devices that a Computer Aided Design (CAD) user might wish to add to the set up above in order to perform his tasks effectively.

Digitizer
Keyboard
USB port

(b) A customer wishes to purchase a computer system. The customer can buy word processor, spreadsheet, database, and a drawing package separately or as an integrated package. State three reasons why the customer would prefer an integrated package to separate packages

The software provides easy movement of data among the separate applications,
A common group of commands is used for all the applications in the software package,
Provides easy switching between functions without having to go back to the operating system and ability to share data between functions.

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Explain two health issues that could arise from the use of unsuitable computer desk.

13/1/2021

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Explain two health issues that could arise from the use of unsuitable computer desk.

It could lead to back problems if the desk is of an unrealistic height.
If it does not provide good positioning of the monitor, it could result in eye strain.
Wrist problems will arise if the keyboard and mouse seating positions are bad.
Injury as a result of falling computer components due to weak computer desks/ small size.

(b i)Describe two ways in which a positive number and a negative number can be represented in a computer

In binary one bit usually the most significant or leading bit is used to indicate either positive or negative,and store the unsigned binary representation of the magnitude in the remaining bits.
Signed magnitude.
Using the twos complement.
Using the ones complement.

(ii) A particular computer stores numbers in a single 8-bit word.
Determine how the number 0.3125 base 10 would be represented.

No.18.(a) Explain two health issues that could arise from the use of unsuitable computer desk. It could lead to back problems if the desk is of an unrealistic height. If it does not provide good positioning of the monitor, it could result in eye strain

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With the aid of a diagram, describe the Hierarchical Database Model.

13/1/2021

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With the aid of a diagram, describe the Hierarchical Database Model.

Data items are arranged in a tree like format.

Access is through a single path and all from one single item called the root component

(b) List three factors that should be considered when developing a database application and give reasons why each should be considered.
Factors

Complexity of data/user needs/user friendliness
Security and integrity
Complexity of DBMS
Volume of data/size
Software compatibility with existing DBMS
Cost of the data base

Reasons

Complexity of data - Complex data requires complex DBMS.
Security and integrity - Data which is intended to be secured in terms of access, can be handled by complex DBMS which provides for such requirements.
Complexity of DBMS - Complex DBMS do require complex skills, hence more training. It is therefore costly to run/use such system.
Volume of data - Voluminous data require to be ran on stable application.
They also take up extra computer system resources.
Software compatibility - enables pre-existing databases to be exported to the new one.

(c) (i) Name three types of validation checks during data entry in data processing.

Field type/data type
Field size
Format
Reasonableness
Range constraint
Presence check

(ii) Differentiate between primary key and index key as used in databases.

Any index key is a database feature used to speed up search and sort operations in a table; whereas
A primary key is a field that enforces uniqueness in a table so that one record is not entered twice or a primary key is a field that uniquely identifies each record.

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Figure 1 shows a flowchart. Use it to answer the questions that follow.

13/1/2021

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Figure 1 shows a flowchart. Use it to answer the questions that follow.

(a) Interpret the flowchart.
(b) Write a pseudo code for the flowchart.

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Explain two ways in which the use of internet could make reporting of corruption easier

10/1/2021

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Explain two ways in which the use of internet could make reporting of corruption easier

(b) Explain two circumstances under which the use of wireless communication would be preferred in data communication.
(c) Figure 2 is an extract of a spreadsheet showing what the students had targeted to score and the actual score in a computer remedial class.

A performance factor is obtained by subtracting the target score from the actual score and dividing the difference by the target score.
Write a formula that uses cell references only that would be entered in cell:
(i) D2 to compute the performance factor.
(ii) E2 to display the statement ‘more remedials’ if the performance factor is less than zero, ‘exempted’ if the factor is greater than zero and ‘optional remedials’ if otherwise.
(iii) D8 to display the best performance factor.

RESPONSES

(a) Ways ¡n which internet makes reporting of corruption easier.

Interactiveness: the internet based technology enables real-time dialogue hence instantaneous reporting of cases;
Outreach: the technology allows the coverage of wide areas/can be reported from anywhere;
Social mobilisation: It is easy to use technology to create a network with people or organisations with similar concerns;
Anonymity: With use of the technology, it has become easy to report corruption cases without being known;
Security: The message sent reaches the destination with less risk of being intruded.

(b) Circumstances when wireless is preferred

When the targetted recipients are many and diverse e.g. different platforms, devices, geographical locations.
When the sender or receiver is mobile and it in practical to use wired media.
When there is no space or it is inconvenient to lay cables e.g in a congested town.
When the distance of travel is very big e.g extraterestial communication.

A performance factor is obtained by subtracting the target score from the actual score and dividing the difference by the target score. Write a formula that uses cell references only that would be entered in cell: (i) D2 to compute the performance factor. (ii) E2 to display the statement ‘more remedials’ if the performance factor is less than zero, ‘exempted’ if the factor is greater than zero and ‘optional remedials’ if otherwise. (iii) D8 to display the best performance factor.

Use of the 1F function
First selection & output
Second selection & output
Last selection & output

(iii) = Max (D2:D7)

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List two techniques of acquiring electronic images to be used in a desktop publishing program.

10/1/2021

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List two techniques of acquiring electronic images to be used in a desktop publishing program.

(ii) Describe two layout guides in a desktop publishing program (DTP) that assist a user to place an object in a preferred position.
(b) Explain three ways of ensuring that data submitted for processing is accurate.
(c)An engineering company requires a computer system to design roads and bridges.
Explain one suitable choice for:
(i) output device;
(ii) software.

RESPONSES

(a) (i) Ways of acquiring images in DTP:

Scanning;
Picture capture via camera;
downloading;
getting from secondary storage.

(ii) Layout guides

Ruler guides: a ruler on the edges of the page that guides a user to position objects and resize them;
Margin guides: used to define page margins so that the user will be prevented from placing objects in non-printable areas of the page;
Column guides: Vertical lines used to divide a page into two or more columns;
Row guides: Lines used to divide a publication page into two or more section to help structure the layout;
Snap points: Positions on the screen where the object is stuck on.

(b) Ways of ensuring accuracy of data during data processing

Data is stored in secondary storage in such a way that access to it is controlled.
Encrypting of data before it is transmitted to minimize chances of it being compromised during transmission.
Use of validation methods to ensure that data is correct at the point of input.
Use of direct data capture methods which eliminates human errors.
Use of verification methods.

(c) (i) Output device: A plotter because it prints large size drawings to high precision.
(ii) A CAD software because it facilitates in the design of engineering drawings.

(ii) Describe two layout guides in a desktop publishing program (DTP) that assist a user to place an object in a preferred position. (b) Explain three ways of ensuring that data submitted for processing is accurate. (c)An engineering company requires a computer system to design roads and bridges. Explain one suitable choice for: (i) output device; (ii) software.

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State three functions of networking operating systems other than providing network security.

10/1/2021

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State three functions of networking operating systems other than providing network security.

(b) Explain three ways in which an operating system provides data security in a computer system.
(c) Explain three circumstances under which observation method may be preferred during data collection.

(a) Functions of network operating systems

Provide access to network resources;
Supporting network services like protocols;
Support communication;
Respond to requests from applications;

(b) Ways in which an operating system provides data security

Access control: Deals with the problem of verifying /authenticating the identity of a user before permitting access to the request resource (e.g. use of passwords, user account);
Encryption - Transforming data into an unreadable format so that they are safely transmitted;
Firewalls - Filters out unwanted data and programs/criminals/hackers/malicious persons;
Log files - A means by which transactions in a computer system can be recorded thereby deterring potential infiltrators;
Alerts - Alerting a user when he/she is about to delete a file/folder.

(c)Preference of observation during data collection

When the subjects that are being observed need not be made aware of the fact;
When there is need to directly see what subjects do rather than rely on what they tell you;
When there is need to collect data without interfering with the working of the subjects;
When nature of data can only be collected via observation e.g. traffic flow;
When collecting data in situation that subjects may be unwilling to give information.

(b) Explain three ways in which an operating system provides data security in a computer system. (c) Explain three circumstances under which observation method may be preferred during data collection.

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In the BCD number coding scheme, letter A is represented by 110001 and letter B by 110010. Determine how the word CAB is coded in BCD.

10/1/2021

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In the BCD number coding scheme, letter A is represented by 110001 and letter B by 110010. Determine how the word CAB is coded in BCD.

(ii) Convert the decimal number 11.125 to its binary number system equivalent.
(iii) Perform the binary arithmetic: 111.01 + 1011.111 — 101.011 and convert the answer to decimal notation.
(b) Explain the importance of each of the following in word processing:
(i) tab stops;
(ii) section breaks.
(c) State three documents that are used during mail merging in word processing.

ANSWERS

(b) Importance of tab stops and section break

(i) Tab stop: when tab stops are set, they allow aligning of text into columns;
(ii) Section breaks: Allows splitting of a document into different sections so that different formatting styles can be applied to the different sections.

Main document - primary/secondary/data source
The address list - the intended recipients of the document.
The merged document - final document ready for printing or sending.

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List four web programming languages.

10/1/2021

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List four web programming languages.

HTML - Hyptertext Mark-up Language
Java script
VBScript - Visual Basic script
XML - Extensible Markup Language
PHP - Hypertext Preprocessor
SQL - Structured Query Language
Dream weaver
Front page

State four ways in which a programmer can make program code easy to fol1ow

Using modules or short blocks of program/functions/procedures;
Making internal documentation / comments;
Using meaningful variable names and user words in the program;
Using indent to represent nested statement:
Using blank lines to separate blocks of code statement;
Test formatting of reserved words e.g. bolding

Draw a program flowchart to represent the following pseudocode.

ANSWER

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Describe the octal number system.

7/1/2021

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Describe the octal number system.

(a) Describe the octal number system.

(b) Convert each of the following to the number system indicated:

(i) 111.101₂ to decimal;

(ii) 14.6875₁₀ to binary.

(i) signed magnitude representation;

(ii) two’s complement.

(d) Perform the arithmetic operation

110.11₂ + 11.011₂

RESPONSES

(a) Characteristics of octal number system.

each symbol is represented by 3 bits.
The number is made of 8 symbols 0. 1. 2,…….. 7;
Maximum value of a single digit is 7 (one less than the value of the base);
This number system uses base 8.

(b) Convert each of the following to the number system indicated: (i) 111.1012 to decimal; (ii) 14.687510 to binary. (c) Convert the number -17 10 into 8-bit: (i) signed magnitude representation; (ii) two’s complement. (d) Perform the arithmetic operation 110.112 + 11.0112

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The following is an extract from a document created using a wordprocessor.

7/1/2021

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The following is an extract from a document created using a wordprocessor.

Identify six formats that have been applied on the extract.
(b) State three tools in a wordprocessor that would help a user to minimize spelling mistakes when creating a document.
(c) The following is an extract of a spreadsheet created to manage sales. Use it to answer the questions that follow.

(i)Write a formula that will compute the number of items whose unit price is more than 10,000.
(ii) If the formula = $R2 * C$2 was placed in cell D2, state the output if it was copied to D3.
(d) A school administers examinations to all students in sciences, humanities and languages. Use the entities; EXAMINATIONS, STUDENTS, SCIENCES,HUMANITIES and LANGUAGES to illustrate a network database model.

RESPONSES

(a) Formats applied

Bold. strikethrough, underline, italics, centre alignment, dropcap, bulleted list, line height / spacing, 2 column paragraph. column break, casing, font type, left alignment, column separator.

(b) Tools for proofreading

Spell checker and grammar/ dictionary;
Autocomplete;
Autocorrect;
Thesaurus.

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With the aid of a diagram. describe time sharing mode as used in computer data processing.

7/1/2021

1 Comment

With the aid of a diagram. describe time sharing mode as used in computer data processing.

(b) A company’s management has opted to use computers to process data. State four factors that the management needs to consider when selecting the company data processing mode.
(c) Explain the purpose of each of the following in system documentation:
(î) user manual;
(ii) sample data:
(iii) table descriptions.

RESPONSES

(a) Time-sharing mode
This is a processing mode in which a central processor serves two or more users with different requirements. The processor time is divided equally
among the tasks in the queue. A user whose task requirements are more than is apportioned is send back to the queue. For example, four jobs requiring times t1, t2, t3 and t4 to complete is apportioned equal time in each round until when they are done.

With the aid of a diagram. describe time sharing mode as used in computer data processing.

(b) Factors to consider when selecting data processing mode

The optimisation of processing time;
The time factor required for decision arising from the processed data;
The ease of development, use and maintenance;
The control over the resources e.g. files, I/O devices e.t.c;
The need for the shared resources among several users who may afford purchasing their own facilities as in time sharing configuration;
The volume of work involved;
The cost of acquiring the relevant hardware. software. media e .t .c and the cost of maintenance;
The nature of the task to be processed.

It is a documentation whose purpose is to help a user to use the system with little guidance.

(ii) Purpose of sample data

Before the system is implemented, it has to be confirmed that it is functional. Sample data is meant to be used to test whether the system is giving desired output.

(iii) Purpose of table descriptions

They are details of table structures that the system will require for the purpose of designing the actual tables.

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State two advantages of using low level programming languages.

7/1/2021

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State two advantages of using low level programming languages.

(b) Other than flowcharts, state three tools that can be used to present an algorithm.
(c) A form one admission interview consists of four tests; Mathematics, English, Kiswahili and Science. In order to qualify for admission, an applicant must attain a minimum average of 65% in the four tests and not less than 70% in Mathematics. All applicants must sit for the interview. Draw a flowchart that would read the scores for each applicant and determine whether an applicant is successful or not.

(a) Advantages of using low-level language

program execution is immediate;
they require no compilation, no interpretation/translation hence they are faster;
hardware optimization is extensive;
program developed takes less memory space;
suitable for micro devices;
easy to design electronic device.

(b) Three tools that can be used to develop an algorithm

Decision table
pseudocode;
natural language;
top down charts;
flowcharts.
DFD/context diagram
ERD
decision tree

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Distinguish between Computer Aided Instruction (CAI) and Computer Aided Learning (CAL).

7/1/2021

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a) Distinguish between Computer Aided Instruction (CAI) and Computer Aided Learning (CAL). (4 marks)

Computer aided instruction is an interactive instructional technique/drill and practice whereby a computer is used to present the instructional material and monitor the learning that takes place. Computer aided learning is the use of computers to aid in the education or training.

b)(i) State four activities that may be carried out when disposing off an old system in an organization. (4 marks)

Confidential information must be removed/Backup.
All accounts or access control facilities associated with the equipment must be destroyed.
Installation of the new system.
All potential clues such as configuration settings must be destroyed
Storage devices which had sensitive information should be destroyed.
The equipment to be disposed in proper manner.

ii) State four ways of getting user specifications during systems design. (4 marks)

Sampling of existing documents
Conduct research and visits the sites
Observation of work environment
Use questionnaires
Conduct interviews
Use prototyping approach
Use Joint Requirement Planning (JRP)
Automated method

a) Distinguish between Computer Aided Instruction (CAI) and Computer Aided Learning (CAL). (4 marks)

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Explain three features of a graphical user interface as used in computers.

7/1/2021

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A) Explain three features of a graphical user interface as used in computers. (6 marks)

Windows — a rectangular area on the screen where the commonly use application run.
Icons — A picture or symbol which is used to represent a software application or hardware device.
Menus —a list of options from which the user can choose what that they require.
Pointer - a symbol such as arrow which moves around the screen as the user move the mouse.

B) State the function of each of the following computer keyboard keys:

(i) Caps Lock (1 mark)
(ii) Shift (1 mark)
(iii) Home (1 mark)

(i) Function of Caps lock
- It’s a toggle key when ON, the characters typed are in uppercase when OFF, the characters typed are in lower case.
(ii) Shift key
- Used to enable uppercase letter to be printed when alphanumeric keys are pressed.
- Used with other keys to modify behavior/function key.
(iii) Home key
- Used to take the cursor to the beginning of the line in a word processor.
- Evidence of movement of the cursor.

C) Using two complement notation, determine the value of the operation 25₁₀ — 29₁₀ (6 marks)

C) Using two complement notation, determine the value of the operation 25 -- 29 (6 marks)

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COMPUTER STUDIES QUESTIONS WITH ANSWERS

​Compute the value of x in the following expressions

Using twos complements compute the following using 8 bits binary (4mks)

​c) Subtract the following binary numbers using the One’s Compliment method. (3mks)

d)Convert 60578 to Hexadecimal. (3mks)

​(a) List and describe four strategies for converting from an old system to a new system. (4mks)

(b) (i) Distinguish between private data and confidential data (2mks)

(ii) What can be done to stop illegal access to a computer laboratory by unauthorized people (3mks)

​(c) (i) List four areas that would be considered in the requirement specification. (4mks)

​(ii) Name any two areas covered in feasibility report during system analysis and design. (2mks)

​The information below is maintained by the sales lady at the school canteen. Study it and answer the questions that follow.

​(a) Describe the basic data types used in this spreadsheet (4mks)

​(b) Provide a single formula that would be used to (i) Count the number of items whose units are equal; to 15 (2mks)

​(ii) Sum the values of items whole units are equal to 12 (2mks)

(c) (i) List and describe four areas of application of spreadsheets (4mks)

(ii) Explain data range legend and axis as used in spreadsheet charts (3mks)

(a) List three advantages and three disadvantages of fibre optic cable (6mks) Advantages

​Disadvantages

​(b) Describe the following signals and state where each is applied in network communication. (4mks) Analog

​Digital

​(c) Name two types of coaxial cables (2mks)

(d) (i) Distinguish between microwave and satellite transmissions. (2mks)

​(ii) Give an example of internet protocol (1mk)

(b) Name the control structures you have used in the flow chart (2mks)

Describe three methods you would use in error detection during program testing

A school has been advised to employ a database administrator. State three responsibilities of this personnel in the school.

Distinguish between a microwave transmission and a radio transmission.

Describe three arithmetic errors that may occur during computerised data processing.

State two qualities of a good pseudocode.

(b) With the aid of flowchart diagrams, describe each of the following programme control structures: (i) sequence (ii) selection

​(c) Draw a programme flowchart that would accept three numbers and find their sum. If the sum is greater than 200. It adds 30 to the sum, otherwise subtracts 20 from the sum. The programme should then display the results.

Explain three ways in which an operating system provides data security in a computer system

Explain two health issues that could arise from the use of unsuitable computer desk.

Explain two health issues that could arise from the use of unsuitable computer desk.

With the aid of a diagram, describe the Hierarchical Database Model.

Figure 1 shows a flowchart. Use it to answer the questions that follow.

Explain two ways in which the use of internet could make reporting of corruption easier

List two techniques of acquiring electronic images to be used in a desktop publishing program.

State three functions of networking operating systems other than providing network security.

In the BCD number coding scheme, letter A is represented by 110001 and letter B by 110010. Determine how the word CAB is coded in BCD.

List four web programming languages.

State four ways in which a programmer can make program code easy to fol1ow

​Draw a program flowchart to represent the following pseudocode.

Describe the octal number system.

(i) 111.1012 to decimal;

(ii) 14.687510 to binary.

(i) signed magnitude representation;

(ii) two’s complement.

The following is an extract from a document created using a wordprocessor.

With the aid of a diagram. describe time sharing mode as used in computer data processing.

State two advantages of using low level programming languages.

​a) Distinguish between Computer Aided Instruction (CAI) and Computer Aided Learning (CAL). (4 marks)

b)(i) State four activities that may be carried out when disposing off an old system in an organization. (4 marks)

​ii) State four ways of getting user specifications during systems design. (4 marks)

​A) Explain three features of a graphical user interface as used in computers. (6 marks)

B) ​State the function of each of the following computer keyboard keys:

C) Using two complement notation, determine the value of the operation 2510 — 2910 (6 marks)

Categories

Archives

Compute the value of x in the following expressions

c) Subtract the following binary numbers using the One’s Compliment method. (3mks)

d)Convert 6057₈ to Hexadecimal. (3mks)

(a) List and describe four strategies for converting from an old system to a new system. (4mks)

(c) (i) List four areas that would be considered in the requirement specification. (4mks)

(ii) Name any two areas covered in feasibility report during system analysis and design. (2mks)

The information below is maintained by the sales lady at the school canteen. Study it and answer the questions that follow.

(a) Describe the basic data types used in this spreadsheet (4mks)

(b) Provide a single formula that would be used to
(i) Count the number of items whose units are equal; to 15 (2mks)

(ii) Sum the values of items whole units are equal to 12 (2mks)

(a) List three advantages and three disadvantages of fibre optic cable (6mks)
Advantages

Disadvantages

(b) Describe the following signals and state where each is applied in network communication. (4mks)
Analog

Digital

(c) Name two types of coaxial cables (2mks)

(ii) Give an example of internet protocol (1mk)

(b) With the aid of flowchart diagrams, describe each of the following programme control structures:
(i) sequence
(ii) selection

(c) Draw a programme flowchart that would accept three numbers and find their sum. If the sum is greater than 200. It adds 30 to the sum, otherwise subtracts 20 from the sum. The programme should then display the results.

Draw a program flowchart to represent the following pseudocode.

(i) 111.101₂ to decimal;

(ii) 14.6875₁₀ to binary.

a) Distinguish between Computer Aided Instruction (CAI) and Computer Aided Learning (CAL). (4 marks)

ii) State four ways of getting user specifications during systems design. (4 marks)

A) Explain three features of a graphical user interface as used in computers. (6 marks)

B) State the function of each of the following computer keyboard keys:

C) Using two complement notation, determine the value of the operation 25₁₀ — 29₁₀ (6 marks)