CG1 Computing June 2009

[1]

A school teacher has to prepare end of year reports for over a hundred pupils. Each report has to include the pupil's name and address and a grade for each subject being studied. All the data required for the reports is stored on the school's computer system.

(a)

Name the facility of a word processor that could be used to combine this data to produce completed reports.

[1]

mail merge

(b)

It is intended that each report will be sent to the pupil's home as an email attachment. Briefly describe a benefit and a potential problem with sending reports home in this way.

[2]

no expenses such as envelopes and stamps
reports may get hacked (intercepted and edited) by unauthorised people or the pupil may delete the email.

[2]

Angharad is building her own personal computer. She has to decide which type of secondary storage devices to use. She considers the use of a floppy disc drive and a hard disc drive.

Recommend two other secondary storage devices that Angharad could use. Compare the speed of access of these devices and describe a typical use for each device.

[5]

CD/DVD writer
magnetic tape drive
The tape drive would have much slower access to stored data than the CD/DVD writer.
The CD/DVD writer could be used to store large files such as music files or films, that could be loaded into other computers.
the tape drive could be used to make a regular backup of all the files stored on the computer.

[3]

The operating system of a desk top computer manages resources and provides an interface between the user and the machine. Describe four features of the user interface provided by the operating system.

allows the user to load and run applications
maintains security by checking usernames and passwords
outputs error messages for the user
allows the user to customise the interface by setting options such as font size, colour schemes, layout etc

[4]

Power Motors is a successful used car dealer. Currently the details about the cars for sale, cars sold and customers are stored in paper files in the office. The business is moving to a larger site.

Currently, paper files are often misplaced and customers cannot be contacted. With the expansion of the business the owner believes that the problems with the current paper-based system will increase.

(a)

Briefly describe two other possible problems with the current paper-based system and describe how a computerised database system could solve these problems.

[4]

searching for details about cars or customers is too slow...
...a database would provide a method of querying the records to retrieve data quickly.
paper files would need to be photocopied if backup copies are required.
...a database system allows easy copying of data.

(b)

The data is collected lawfully and will not be held longer than necessary. Describe four other ways in which the Data Protection Act will apply to the data stored by Power Motors.

[4]

the data must only be held for a specified purpose
the data stored must be relevant and not more than is necessary for the specified purpose
the data must be accurate and kept up-to-date
the data must be kept secure

[5]

A firm of accountants currently use a number of stand-alone personal computers. They decide to update their computer system and employ a computer consultant to make recommendations about a possible new computer system.

The consultant makes several recommendations.

(a)(i)

The first recommendation is to have a computer network using a star network topology.

Draw a diagram that illustrates the star topology, giving one advantage of using a star network topology rather than other topologies.

[2]

A reliable network. Breakdown in one workstation link does not affect the rest of the network.

(ii)

Apart from sharing hardware, describe in detail two reasons why the consultant might recommend installing a network.

[2]

data can be shared - a database can be stored on one computer on the network and accessed by all other computers.
computers can easily communicate with each other - emails, messages etc.

(b)

The second recommendation is to issue the accountants with laptop computers so that they can work at any desk in the office and also use the laptop computers when out of the office visiting clients.

(i)

Name the hardware required for the network and for each laptop computer to enable wireless communication between each laptop computer and the office network.

[2]

each laptop will need a wireless network card
a wireless hub would need to be connected to the network to beam the signals to the laptops.

(ii)

Briefly describe how an accountant could communicate using their wireless laptop computer from a client's premises.

[1]

connect to the client's wireless network, and then send message/email over the Internet.

[6]

Data being stored on a computer in an estate agent's office is subject to validation checks.

(a)

Briefly describe when validation checks are carried out and their purpose.

[2]

checks are carried out on the data when it is input and before it is processed
...to make sure that data is sensible.

(b)

Briefly describe a validation check that would sensibly be carried out on the number of bedrooms in a house. Give an example of invalid data that would be detected by this check.

[2]

type check - data must be an integer
invalid data : 3.5

[7]

Sales persons in a mobile phone shop receive commission for the number of phones they sell each month.

When a sale is made they record details including the phone number, for example 07734 234567 and the customer's gender, M or F.

(a)

State the data type that would be the most suitable for storing the phone number.

[1]

string

(b)

State the data type that would be the most suitable for storing the gender of the customer.

[1]

character

(c)

The monthly sales data for each sales person are recorded as shown below:

Staff Code	Total number of phones sold each month
	Jan	Feb	Mar	Apr	May	...
001	34	43	23	...	....	...
002	26	47	54	...	...	...
003	...	...	...	...	...	...
...	...	...	...	...	...	...

(i)

State the full name of this type of data structure.

[1]

two-dimensional array

(ii)

State the data type that would be most suitable for storing the total number of phones sold each month.

[1]

integer

(iii)

State the data structure that would be most suitable to store the customer and phone information, briefly describing why it is most suitable data structure.

[2]

a record
there would be a number of fields of different data types.

[8]

Many people, including children, use social networking web sites. The users have profiles on these sites where they can post personal information about themselves and describe their interests. These sites allow them to make new friends and share ideas, music and videos.

Discuss the benefits and drawbacks of using social networking web sites.

[5]

users can make new friends by selecting people with similar interests
friends can keep in touch from anywhere in the world
people with similar interests can get together and discuss or exchange information.
people may not give accurate information, and criminals may pretend to be somebody they are not.
personal information may be used for inappropriate purposes (blackmail, stalking, harassment, bullying)
social skills may be lost because of lack of real contact

[9](a)

Name an application where real time transaction processing is necessary. Explain how real time transaction processing operates in this case and give one reason why real time transaction processing is necessary.

[3]

Eg. a train seat booking system
As soon as a customer books a seat on a train, the files are updated to show that the seat is booked.
there can be no double booking - two customers cannot book the same seat.

(b)

Name an application where real time control processing is necessary. Explain how real time control processing operates in this case and give one reason why real time control processing is necessary.

[3]

Eg. computer-controlled glass manufacturing
sensors input readings to the computer, which outputs control signals to the machinery making the glass
immediate response to variations (in temperature) ensures high quality manufacture and minimal number of accidents

[10]

Below is an algorithm to determine the largest of three integers.

Algorithm FindBiggest

Num1 is integer			{number input by user}
Num2 is integer			{number input by user}
Num3 is integer			{number input by user}
Biggest is integer			{stores the biggest number}

startmainprog

	repeat		{input and validate Num1}
		input Num1
	until (Num1 is an integer)

	repeat		{input and validate Num2}
		input Num2
	until (Num2 is an integer)

	repeat		{input and validate Num3}
		input Num3
	until (Num3 is an integer)

	set Biggest = Num1

	if Num2 > Biggest then Biggest = Num2
	if Num3 > Biggest then Biggest = Num3

	output Biggest

endmainprog

(a)

Write down one example of a global variable from the algorithm.

[1]

Num1 (or Num2, Num3, Biggest)

(b)

Write down one example of annotation from the algorithm and explain why annotation is used in computer programs.

[2]

{input and validate Num1}

(c)

Using an example from the algorithm, describe in detail the purpose of repetition in computer programs.

[3]

repeat
input Num1
until (Num1 is an integer)
the line [input Num1] is repeatedly executed ...
...until a condition is met. (Num1 is an integer). The user keeps entering data until the data input is a valid integer.

(d)

Using an example from the algorithm, describe in detail the purpose of selection in computer programs.

[3]

if Num2 > Biggest then Biggest = Num2
if the condition (Num2 > Biggest) is true, then the line (Biggest = Num2) is executed...
...otherwise the line is not executed.

[11]

The Government is very worried about the amount of petrol being used and the amount of pollution caused by cars in this country. The Government is considering whether to charge yearly tax for all the petrol cars in the country according to the official petrol consumption figures (in miles per gallon) and the carbon dioxide emissions produced (in grammes per km).

The algorithm under consideration is shown below:

1	input Emission
2	input Consumption
3	if ((Emission>170) OR ((Emission>160) AND (Consumption<35)))
4		then output "£200 tax"
5		else if ((Emission>150) OR ((Emission>140) AND (Consumption<35)))
6			then output "£150 tax"
7			else output "£100 tax"

(a)(i)

State what the output will be when the inputs are:
Emission = 135 Consumption = 30

[1]

£100 tax

(ii)

State what the output will be when the inputs are:
Emission = 175 Consumption = 40

[1]

£200 tax

(iii)

State what the output will be when the inputs are:
Emission = 145 Consumption = 40

[1]

£100 tax

(iv)

State what the output will be when the inputs are:
Emission = 155 Consumption = 40

[1]

£150 tax

(b)

A change is made in line 5 of the algorithm as shown below:

5	else if ((Emission>150) OR (Consumption<35))

(i)

State which of parts (a)(i) to (a)(iv) now gives a different output.

[1]

(a)(i) would now be £150 tax

(ii)

Briefly explain why the Government may have made this change.

[1]

to charge a higher tax for all cars with low petrol consumption no matter what their emissions are.

[12]

A specialist shop repairs antique clocks and watches, and keeps quite a large supply of suitable spare parts. Sometimes, however, a part may be required which is not kept in stock by the shop. When this happens, the shop owner contacts a national trade organisation which keeps a larger range of spare parts in stock.

The situation described is shown below:

(a)

Diagrams like this are often used in discussion between software developers and users. Give one reason why this is the case.

[1]

diagrams are easier to understand than large amounts of text.

(b)

What type of object does the following shape represent?

[1]

data store

(c)

Write down the shape used in the diagram to represent a data flow.

[1]

an arrow

(d)

Give a suitable name for the object shown as a in the diagram.

[1]

shop's stock database

(e)

Give a suitable name for the object shown as b in the diagram.

[1]

shop availability

(f)

Give a suitable name for the object shown as c in the diagram.

[1]

trade organisation stock database

(g)

Give a suitable name for the object shown as d in the diagram.

[1]

check if in stock at trade organisation

[13]

Below is an algorithm which calculates the mean of a series of positive integers input by a user.

Algorithm FindMean

Num is integer		{number input by user}
Total is integer		{stores the total of the numbers input}
Count is integer		{stores the count of the numbers input}
Mean is real		{stores the mean of the numbers input}

startmainprog
	set Total = 0		{initialise variables}
	set Count = 0
	set Mean = 0

	output "type in first number"
	input Num		{input first number}

	repeat
		set Total = Total + Num
		set Count = Count + 1

		output "type in next number"
		input Num	{input subsequent numbers}
	until (Num < 0)

	set Mean = Total / Count
	output "The mean is", Mean

endmainprog

Complete the table below to show how each variable changes when the algorithm is performed on the test data 7, 2, 5 and 6.

Num	Total	Count	Mean
	0	0	0
7	7	1	0
2	9	2	0
5	14
6
-1

Num	Total	Count	Mean
	0	0	0
7	7	1	0
2	9	2	0
5	14	3	0
6	20	4	0
-1	20	4	5

[14]

Explain how a binary search is used to locate an element called SearchValue in an array called SearchArray.

[3]

the 'middle' element of SearchArray is compared with SearchValue...if equal, then the element is found...
...if middle element is less than SearchValue, then the first half of the array is discarded. If it is greater, then the second half of the list is discarded...
...and the process is repeated, until SearchValue is found (or there are no more elements in the array, in which case SearchValue is not in the array SearchArray)

[15]

Computers have both ROM and RAM memory.

(a)

Briefly describe the difference between these types of memory.

[2]

ROM - Read Only Memory - is used for permanent storage of data. Data stored in ROM cannot be altered.
RAM - Random Access Memory - is used for temporary storage of data. Data stored in RAM can be changed.

(b)

Give examples of what would be sensibly stored in each of these types of memory.

[2]

ROM - Operating system program for booting the computer.
RAM - A document being edited with a word processor.

[16]

An electricity supply company uses serial and sequential files. The amount of electricity used by each customer is read from their electricity meter and stored in a serial file called the transaction file. The details about each customer and their previous electricity usage are stored in a sequential file called the master file.

(a)

Briefly describe why a serial file is the most suitable for storing the amount of electricity used.

[1]

new records can be added onto the end of the file.

(b)

Briefly describe why a sequential file is the most suitable for storing details about each customer.

[1]

customer records are sorted, so it is faster for the computer to find a specific record.

(c)

Draw a fully labelled diagram that clearly shows how the master file is updated using a transaction file when the electricity company produces customer bills.

[4]

xxx

[17]

Customers of an on-line auction web site access their accounts using the Internet. When they are logged onto the web site they are able to view items for sale, place a bid for an item, make payments and leave customer feedback. These accounts could be subject to malicious damage.

Define the term malicious damage and give an example of malicious damage that a customer could suffer with an on-line auction account, explain how the auction web site could prevent malicious damage.

[3]

deliberate altering of data in files.
a customer might have their information changed or deleted.
each customer should be given a username and password to log in. Only then could they make a bid.

[18]

A bank, which has branches in most towns and cities in Britain, requires a new computer system. They have employed a team of analysts to develop this new computer system.

In order to understand the current system the analysts are going to carry out a thorough investigation.

Discuss the different methods of investigation available to the analysts justifying their suitability for different situations.

It is very important that the computer users, who will range from novices to experts, find the new system easy to use. Describe in detail the features you would expect to find in the human computer interface that the novice user would find useful and the features that the expert user would find useful.

[12]

The analysts could carry out interviews with the managers. This would allow them to get detailed answers to questions, and to ask further questions based on the received information.
They could also use questionnaires to find out information from the staff. This allows a large number of responses in a short time.
They could also observe current practice, spending some time looking at what jobs the staff in the banks do, and how they do it. This would be useful for finding out problems that occur in the daily running of the bank.
Existing documentation such as user manuals, or staff information sheets should also be read to find out what the staff are currently expected to do.
Novice users would need an easy-to-use and intuitive method of input. Meaningful icons could be used for selection of applications, and a pointing device such as a mouse pointer to click on them. They would also benefit from consistency across many programs, eg. the icon for printing should look the same on all applications. he system should be robust and not crash.
Expert users would benefit from a fast interface that allows them to select many different options such as font size, colours, layout of screens and be able to save these personalised settings. Shortcut keys should be available to perform common tasks. There should be good help facilities if needed.