SPSS 2020 Computing P1 Solution

READ THESE INSTRUCTIONS FIRST Write your name, class, index number in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total number of marks for this paper is 80. Parent’s Signature : ____________________________ Date: ____________________________ Remarks (if any) : For Examiner’s Use Marks /80 Total % This document consists of 11 printed pages including this page. ST. PATRICK'S SCHOOL PRELIMINARY EXAMINATIONS 2020 SECONDARY 4 EXPRESS NAME Marking Scheme CLASS INDEX NUMBER COMPUTING Paper 1 Written 7155/01 20 August 2020 2 h Candidates answer on the Question Paper. No Additional Materials are required.

2 1 (a) Convert the binary number 0101 1111 into its hexadecimal value. 5F with correct working [1] (b) Convert the positive whole denary number 462 into a 12-bit binary number. Correct working (place value method or divide-by-2 method) Answer: 0001 1100 1110 [2] (c) Describe how the hexadecimal number 8A is converted into its denary value. Give the denary value in your answer. Description: To convert a hexadecimal number to its denary equivalent: 1. Convert each hexadecimal digit to its equivalent denary number. 2. Multiply each denary number by its place value. 3. Sum the product of each denary number and its place value. Denaryl value: 138 [4]

3 2 The following diagram shows five network terms and six descriptions. Draw a line from each network device to its best description. Network Devices Description Bridge A device that constructs a single network by connecting two similar networks together Router A device responsible for modulation and demodulation Network Interface Card (NIC) A device that provides the hardware interface to enable the transfer of data between a device and a network. Modem A device that extends the distance a signal can travel Hub A device that forwards packets between separate networks A device that transmits received packets to all connected devices [5]

4 3 The following pseudo-code algorithm validates the age of a user. 1 2 3 4 5 6 7 8 9 10 11 is_valid = False no_of_users = 0 CURRENT_YEAR = 2020 WHILE is_valid = False OUTPUT “Enter your birth year: ” INPUT birth_year IF CURRENT_YEAR – birth_year >= 18 THEN is_valid = True no_of_users = no_of_users + 1 ENDIF ENDWHILE (a) The algorithm is tested using the following three numbers as input: 2006, 2000. Complete the trace table for the algorithm. birth_year is_valid no_of_users False 0 2006 False 0 2000 True 1 [3] (b) State whether is_valid is a variable or a constant. Give a reason for your choice. It is a variable A constant is a name with an associated value that usually cannot be changed while the program is running [2] (c) Identify the data validation technique used in the algorithm. Try again [1] (d) Identify two other data validation checks. 1: Length check 2: Presence check, Format check [2]

5 (e) The algorithm is tested with data for normal conditions. Identify two other test case conditions that could be used to test the algorithm. For each condition, give an example of test data for this algorithm. Test case condition 1: Error Test data 1: Any input that is not a positive integer. Test case condition 2: Boundary Test data 2: 2002, 2001, 2003 [4] 4 A government agency has asked your company to create an app for citizens to access all government services. • The app will display a menu that lets the user login or register for an account. • If the user registers for an account, the user must fill up a particulars form. • If the user logs in, he/she will have to pass a few authentication measures before he/she can be granted access. • Once access is given, the user will be able to select a list of government services. • The user can also access his/her email inbox to view/send messages from/to various government services. • The user can log out from the app at any time. (a) Identify five modules that can be decomposed from the problem. Module 1: Login and Register module. Describe the features Module 2: Particulars form Describe the features Module 3: Authentication form Describe the features Module 4: Menu of government services Describe the features Module 5: Email inbox/log off Describe the features [5]

6 (b) For the login module, state the input, output and process that are required. Input: username, password Output: Authentication page Process: store username and password in an array. Search the registered users list for a match. If matches, allow user to go to next page. If not, send error message [3] 5 (a) Draw a logic circuit to represent the following Boolean statement. Do not simplify the statement. X = (NOT A OR (B NOR C)) AND (A NAND C) NOT – 1 OR – 1 NOR – 1 AND – 1 NAND – 1 With correct inputs and output [5] X A B C

7 (b) Complete the following truth table for the Boolean statement: X = (NOT A OR (B NOR C)) AND (A NAND C) A B C Working space X 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 [4] 6 An e-commerce company uses technology to train its staff. (a) Give three social benefits to the staff of using technology to upgrade their skills. 1: On the positive side, technology has provided better videos, simulations and collaboration tools for lessons to be more engaging and relevant to staff. The open sharing of information on the Internet has made education accessible to all, giving a wider perspective. [3] (b) One negative impact of using technology in a company is that its sensitive data can be compromised by cyber-attackers. State two types of cyberattacks. 1: Trojan horse, virus, worm, 2: phishing, pharming, spyware [2] (c) Describe two ways in which the company can adopt to ensure the security and integrity of its customers’ data. 1: Viruses, worms, spyware and Trojan horses are all examples of malware that need to run on a user’s computer in order to perform their respective attacks. Anti-virus and anti-spyware programs can be used to: • detect when malware is about to be run and stop it from running; • detect malware that is already running and try to stop it; or • scan the user’s storage and email to detect and remove malware; if a program has been infected by a virus, it may also try to restore the original program. 2: Update software regularly so that bugs that were discovered since the last update can be fixed. This is especially important for software that is used to interact with public networks such as the Internet, as data from public networks is more likely to be malicious and designed to take advantage of known bugs. Identify phishing, pharming, with correct explanation [4]

8 7 Alice has a $65 000 loan to buy a car. The loan is repaid over 3 years. The interest rate is 10% per year. She has a spreadsheet to keep track of the repayments and the amount she owes. A B C D E 1 Initial Loan $65,000.00 Total Paid to Date $4,194.74 2 Interest Rate 10% Amount Owed $71,310.00 3 Loan Length (months) 36 Num