Cambridge IGCSE Computer Science (9-1) 0984 — 2023 May/June Paper 2 · Variant 1

This document has 16 pages. Any blank pages are indicated. [Turn over Cambridge IGCSE™(9–1) COMPUTER SCIENCE 0984/21 Paper 2 Algorithms, Programming and Logic May/June 2023 1 hour 45 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● Calculators must not be used in this paper. INFORMATION ● The total mark for this paper is 75. ● The number of marks for each question or part question is shown in brackets [ ]. ● No marks will be awarded for using brand names of software packages or hardware. * 3 8 0 6 2 5 0 5 3 4 * DC (KS) 326836 © UCLES 2023

2 0984/21/M/J/23 © UCLES 2023 1 (a) Four descriptions of stages in the program development life cycle are shown. Draw one line to link each description to its most appropriate program development life cycle stage. Not all program development life cycle stages will be used. Program development life cycle description Program development life cycle stage develop an algorithm to solve the problem by using structure diagrams, flowcharts or pseudocode analysis coding design evaluation testing detect and fix the errors in the program identify the problem and its requirements write and implement the instructions to solve the problem [4] (b) Identify three of the component parts after a problem has been decomposed. 1 … … 2 … … 3 … … [3] 2 Tick (ü) one box to show the name of the data structure used to store a collection of data of the same data type. A Array B Constant C Function D Variable [1]

3 0984/21/M/J/23 © UCLES 2023 [Turn over 3 (a) Describe what is meant by data validation. … … … … [2] (b) A validation check is used to make sure that any value that is input is an integer between 30 and 200 inclusive. Give one example of each type of test data to check that the validation check is working as intended. Each example of test data must be different. Give a reason for each of your choices of test data. Normal test data … Reason … … Abnormal test data … Reason … … Extreme test data … Reason … … [6] 4 Explain the purpose of the library routines DIV and ROUND DIV … … … … ROUND … … … … [4]

4 0984/21/M/J/23 © UCLES 2023 5 An algorithm has been written in pseudocode to allow some numbers to be input. All the positive numbers that are input are totalled and this total is output at the end. An input of 0 stops the algorithm. 01 Exit ← 1 02 WHILE Exit <> 0 DO 03 INPUT Number 04 IF Number < 0 05 THEN 06 Total ← Total + Number 07 ELSE 08 IF Number = 0 09 THEN 10 Exit ← 1 11 ENDIF 12 ENDIF 13 ENDIF 14 OUTPUT "The total value of your numbers is ", Number (a) Identify the four errors in the pseudocode and suggest a correction for each error. Error 1 … Correction … … Error 2 … Correction … … Error 3 … Correction … … Error 4 … Correction … … [4]

5 0984/21/M/J/23 © UCLES 2023 [Turn over (b) Describe how you could change the corrected algorithm to record and output how many positive numbers have been included in the final total. You do not need to rewrite the algorithm. … … … … … … … … [4] 6 State two features that should be included to create a maintainable program. Give a reason why each feature should be used. 1 … … … … 2 … … … … [4]

6 0984/21/M/J/23 © UCLES 2023 7 The flowchart represents an algorithm. START INPUT Letter INPUT Choice OUTPUT "Another Letter? (Y or N)" OUTPUT "Letter ", Letter, " is represented by ", Word[Pointer, 2] IS Choice = 'Y' ? IS Word[Pointer, 1] = Letter ? STOP Pointer 1 Pointer Pointer + 1 Yes Yes No No

7 0984/21/M/J/23 © UCLES 2023 [Turn over The table represents the two-dimensional (2D) array Word[] which stores the first half of the phonetic alphabet used for radio transmission. For example, Word[10,1] is ‘J’. Index 1 2 1 A Alpha 2 B Bravo 3 C Charlie 4 D Delta 5 E Echo 6 F Foxtrot 7 G Golf 8 H Hotel 9 I India 10 J Juliet 11 K Kilo 12 L Lima 13 M Mike (a) Complete the trace table for the algorithm by using the input data: F, Y, D, N Pointer Letter Choice OUTPUT [4]

8 0984/21/M/J/23 © UCLES 2023 (b) Identify the type of algorithm used. … … [1] (c) Describe one problem that could occur with this algorithm if an invalid character was input. … … … … [2]

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10 0984/21/M/J/23 © UCLES 2023 8 The function LENGTH(Phrase) calculates the length of a string Phrase (a) Write the pseudocode statements to: • store the string "The beginning is the most important part" in Phrase • calculate and output the length of the string • output the string in upper case. … … … … … … [3] (b) Write the output your pseudocode should produce. … … … … [2]

11 0984/21/M/J/23 © UCLES 2023 [Turn over 9 Consider this logic expression. Z = (NOT A OR B) AND (B XOR C) (a) Draw a logic circuit for this logic expression. Each logic gate must have a maximum of two inputs. Do not simplify this logic expression. A B C Z [4] (b) Complete the truth table from the given logic expression. A B C Working space Z 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [4]

12 0984/21/M/J/23 © UCLES 2023 10 A database table called TVRange shows the main features and prices of a range of televisions. TVCode ScreenSize Satellite SmartTV SoundBar Price$ TV90SaSmSd 90 YES YES YES 9750.00 TV75SaSmSd 75 YES YES YES 8500.00 TV75SaSd 75 YES NO YES 8000.00 TV65SaSmSd 65 YES YES YES 6000.00 TV65SmSd 65 NO YES YES 5000.00 TV65SaSd 65 YES NO YES 5000.00 TV55SaSmSd 55 YES YES YES 4000.00 TV55SaSd 55 YES NO YES 3500.00 TV55SmSd 55 NO YES YES 3500.00 TV50SaSmSd 50 YES YES YES 2500.00 TV50Sa 50 YES NO NO 1750.00 TV50Sm 50 NO YES NO 1750.00 TV40Sa 40 YES NO NO 1200.00 TV40 40 NO NO NO 950.00 TV32 32 NO NO NO 650.00 (a) Give the name of the field that is most suitable to be the primary key. State the reason for this choice. Field … Reason … … [2]

13 0984/21/M/J/23 © UCLES 2023 [Turn over (b) The database uses the data types: • text • character • Boolean • integer • real • date/time. Complete the table to show the most appropriate data type for each field. Each data type must be different. Field Data type TVCode ScreenSize SmartTV Price$ [2] (c) Complete the structured query language (SQL) query to return the television (TV) code, screen size and price of all Smart TVs in the database table. SELECT TVCode, …, … … TVRange WHERE SmartTV = …; [4]

14 0984/21/M/J/23 © UCLES 2023 11 A one-dimensional (1D) array Days[] contains the names of the days of the week. A two-dimensional (2D) array Readings[] is used to store 24 temperature readings, taken once an hour, for each of the seven days of the week. A 1D array AverageTemp[] is used to store the average temperature for each day of the week. The position of any day’s data is the same in all three arrays. For example, if Wednesday is in index 4 of Days[], Wednesday’s temperature readings are in index 4 of Readings[] and Wednesday’s average temperature is in index 4 of AverageTemp[] The temperature readings are in Celsius to one decimal place. Temperatures can only be from –20.0 °C to +50.0 °C inclusive. Write a program that meets the following requirements: • input and validate the hourly temperatures for one week • calculate and store the average temperature for each day of the week • calculate the average temperature for the whole week • convert all the average temperatures from Celsius to Fahrenheit by using the formula Fahrenheit = Celsius * 9 / 5 + 32 • output the average temperature in Celsius and in Fahrenheit for each day • output the overall average temperature in Celsius and in Fahrenheit for the whole week. You must use pseudocode or program code and add comments to explain how your code works. You do not need to declare any arrays, variables or constants; you may assume that this has already been done. All inputs and outputs must contain suitable messages. All data output must be rounded to one decimal place. You will need to initialise and populate the array Days[] at the start of the program. … … … … … … … … … … … …

15 0984/21/M/J/23 © UCLES 2023 … … … … … … … … … … … … … … … … … … … … … … … … … … … … [Turn over

16 0984/21/M/J/23 © UCLES 2023 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. … … … … … … … … … … … … … … … … … … … … … … … … [15]

This document consists of 18 printed pages. © UCLES 2023 [Turn over Cambridge IGCSE™ (9–1) COMPUTER SCIENCE 0984/21 Paper 2 Algorithms, Programming and Logic May/June 2023 MARK SCHEME Maximum Mark: 50 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the May/June 2023 series for most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 2 of 18 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with:  the specific content of the mark scheme or the generic level descriptors for the question  the specific skills defined in the mark scheme or in the generic level descriptors for the question  the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, or other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively:  marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate  marks are awarded when candidates clearly demonstrate what they know and can do  marks are not deducted for errors  marks are not deducted for omissions  answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level descriptors.

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 3 of 18 GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may be limited according to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or grade descriptors in mind.

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 4 of 18 Question Answer Marks 1(a) One mark for each correct line. Program development life cycle description Program development life cycle stage 4 1(b) One mark for naming or describing each component part, max three For example: inputs // what is put into the system processes // actions taken to achieve a result outputs // what is taken out of the system storage // what needs to be kept for future use 3 identify the problem and its requirements develop an algorithm to solve the problem using structure diagrams, flowcharts or pseudocode detect and fix the errors in the program write and implement the instructions to solve the problem analysis design testing evaluation coding

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 5 of 18 Question Answer Marks 2 A 1 Question Answer Marks 3(a) One mark per mark point, max two  Validation is an automated check carried out by a computer  … to make sure the data entered is sensible/acceptable/reasonable 2 3(b) One mark for each appropriate test data, max three One mark for each correct accompanying reason, max three For example: Normal – 75 Reason – the data lies within the required range and should be accepted Abnormal – Sixty Reason – this is the wrong data type and should be rejected Extreme – 200 Reason – the highest value in the required range that should be accepted 6

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 6 of 18 Question Answer Marks 4 One mark per mark point, max four DIV, max two  To perform integer division  Meaning only the whole number part of the answer is retained  Example of DIV For example DIV(9,4) = 2 ROUND, max two  To return a value rounded to a specified number of digits / decimal places  The result will either be rounded to the next highest or the next lowest value  … depending on whether the value of the preceding digit is >=5 or <5  Example of ROUND for example, ROUND(4.56, 1) = 4.6 4

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 7 of 18 Question Answer Marks 5(a) One mark per mark point, max four  Line 04 / IF Number < 0 should be IF Number > 0  Line 10 / Exit  1 // Line 01/ Exit  1 and Line 02 / WHILE Exit <> 0 should be Exit  0 // should be Exit  0 and WHILE Exit = 0  Line 13 / ENDIF should be ENDWHILE  Line 14 / OUTPUT "The total value of your numbers is ", Number should be OUTPUT "The total value of your numbers is ", Total Correct algorithm: 01 Exit  1 02 WHILE Exit <> 0 DO 03 INPUT Number 04 IF Number > 0 05 THEN 06 Total  Total + Number 07 ELSE 08 IF Number = 0 09 THEN 10 Exit  0 11 ENDIF 12 ENDIF 13 ENDWHILE 14 OUTPUT "The total value of your numbers is ", Total 4

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 8 of 18 Question Answer Marks 5(b) One mark per mark point, max four  Initialise a new (counting) variable  … Count  0 // to count the acceptable numbers  Insert a counting statement between lines 05 and 07  … Count  Count + 1  Add a new output after the loop/after line 13 / at the end (of the program)  … OUTPUT Count 4 Question Answer Marks 6 One mark for each correct feature, max two One mark for each correct accompanying reason, max two For example: Meaningful identifiers – to enable the programmer (or future programmers) to easily recognize the purpose of a variable / array / constant // to enable easy tracking of a variable / constant / array through the program Use of comments – to annotate each section of a program so that a programmer can find specific sections / so that the programmer knows the purpose of that section of code Procedures and functions – to make programs modular and easier to update / add functionality 4

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 9 of 18 Question Answer Marks 7(a) One mark per correct column, max four Pointer Letter Choice OUTPUT 1 F 2 3 4 5 6 Letter F is represented by Foxtrot Another Letter? (Y or N) Y 1 D 2 3 4 Letter D is represented by Delta Another Letter? (Y or N) N 4 7(b) (Linear) search 1

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 10 of 18 Question Answer Marks 7(c) One mark per mark point, max two  The algorithm would not stop  … because it would not have found the item it was seeking Or  The array would run out of values after the pointer reached 13  the algorithm will crash 2 Question Answer Marks 8(a) One mark per mark point, max three  Storing string in Phrase  Correct use of LENGTH function  Correct use of UCASE function  Correct outputs of LENGTH and UCASE For example: Phrase  "The beginning is the most important part" OUTPUT LENGTH(Phrase) OUTPUT UCASE(Phrase) 3 8(b) One mark for each correct line, max two 40 THE BEGINNING IS THE MOST IMPORTANT PART 2

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 11 of 18 Question Answer Marks 9(a) One mark for each correct gate, with the correct input(s) as shown. 4

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 12 of 18 Question Answer Marks 9(b) Four marks for eight correct outputs. Three marks for six or seven correct outputs. Two marks for four or five correct outputs. One mark for two or three correct outputs A B C Z 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 1 1 1 1 0 4 Question Answer Marks 10(a) One mark for the correct field name One mark for the correct reason For example: TVCode Each entry in this field is a unique identifier 2

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 13 of 18 Question Answer Marks 10(b) Two marks for four correct answers. One mark for two or three correct answers. Field Data type TVCode Text ScreenSize Integer SmartTV Boolean Price$ Real 2 10(c) One mark for each correct answer ScreenSize Price$ FROM YES Correct code: SELECT TVCode, ScreenSize, Price$ FROM TVRange WHERE SmartTV = YES; 4

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 14 of 18 Question Answer Marks 11 Read the whole answer: Check if each requirement listed below has been met. Requirements may be met using a suitable built-in function from the programming language used (Python, VB.NET or Java). On place a SEEN mark if requirement met, cross if no attempt seen, omission mark and/or comment if partially met (see marked scripts). Use the tables for AO2 and AO3 below to award a mark in a suitable band using a best fit approach, then add up the total:  AO2 (maximum 9 marks)  AO3 (maximum 6 marks) Data structures required: The names underlined must match those given in the scenario: Arrays or lists Days[], Readings[], AverageTemp[] Variables WeekLoop, DayLoop, InTemp, TotalDayTemp, TotalWeekTemp, AverageWeekTemp Requirements (techniques): R1 Input and store hourly temperatures and validation of input temperatures for each day (with prompts, range check and (nested)iteration) R2 Calculate, round to one decimal place and store daily average temperatures and calculate the weekly average temperature rounded to one decimal place (iteration, totalling and rounding) R3 Convert all average temperatures to Fahrenheit (to one decimal place) and output the average temperatures in both Celsius and Fahrenheit. Output with appropriate messages. (output and rounding) 15

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 15 of 18 Question Answer Marks 11 Example 15 mark answer in pseudocode // meaningful identifiers and appropriate data structures for // all data required DECLARE Days : ARRAY[1:7] OF STRING DECLARE Readings : ARRAY[1:7, 1:24] OF REAL DECLARE AverageTemp : ARRAY[1:7] OF REAL DECLARE WeekLoop : INTEGER DECLARE DayLoop : INTEGER DECLARE InTemp : REAL DECLARE TotalDayTemp : REAL DECLARE TotalWeekTemp : REAL DECLARE AverageWeekTemp : REAL // initial population of Days[] array // input and a loop are also acceptable Days[1]  "Sunday" Days[2]  "Monday" Days[3]  "Tuesday" Days[4]  "Wednesday" Days[5]  "Thursday" Days[6]  "Friday" Days[7]  "Saturday" // input temperatures inside nested loop FOR WeekLoop  1 TO 7 TotalDayTemp  0 FOR DayLoop  1 TO 24 OUTPUT "Enter temperature ", DayLoop, " for ", Days[WeekLoop]

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 16 of 18 Question Answer Marks 11 INPUT InTemp // validation of input for between -20 and +50 inclusive WHILE InTemp < -20.0 OR InTemp > 50.0 DO OUTPUT "Your temperature must be between -20.0 and +50.0 inclusive. Please try again" INPUT InTemp ENDWHILE Readings[WeekLoop, DayLoop]  InTemp // totalling of temperatures during the day TotalDayTemp  TotalDayTemp + ROUND(InTemp, 1) NEXT DayLoop // average temperature for the day AverageTemp[WeekLoop]  ROUND(TotalDayTemp / 24,1) NEXT WeekLoop // calculate the average temperature for the week TotalWeekTemp  0 FOR WeekLoop  1 TO 7 TotalWeekTemp  TotalWeekTemp + AverageTemp[WeekLoop] NEXT WeekLoop AverageWeekTemp  ROUND(TotalWeekTemp / 7,1) // outputs in Celsius and Fahrenheit FOR WeekLoop  1 TO 7 OUTPUT "The average temperature on ", Days[WeekLoop], " was ", AverageTemp[WeekLoop], " Celsius and ", ROUND(AverageWeekTemp * 9 / 5 + 32), 1, " Fahrenheit" NEXT WeekLoop OUTPUT "The average temperature for the week was ", AverageWeekTemp," Celsius and ", ROUND(AverageWeekTemp * 9 / 5 + 32, 1)," Fahrenheit"

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 17 of 18 Marking Instructions in italics AO2: Apply knowledge and understanding of the principles and concepts of computer science to a given context, including the analysis and design of computational or programming problems 0 1–3 4–6 7–9 No creditable response. At least one programming technique has been used. Any use of selection, iteration, counting, totalling, input and output. Some programming techniques used are appropriate to the problem. More than one technique seen applied to the scenario, check the list of techniques needed. The range of programming techniques used is appropriate to the problem. All criteria stated for the scenario have been covered by the use of appropriate programming techniques, check the list of techniques needed. Some data has been stored but not appropriately. Any use of variables or arrays or other language dependent data structures e.g. Python lists. Some of the data structures chosen are appropriate and store some of the data required. More than one data structure used to store data required by the scenario. The data structures chosen are appropriate and store all the data required. The data structures used store all the data required by the scenario.

0984/21 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2023 © UCLES 2023 Page 18 of 18 Marking Instructions in italics AO3: Provide solutions to problems by:  evaluating computer systems  making reasoned judgements  presenting conclusions 0 1–2 3–4 5–6 No creditable response. Program seen without relevant comments. Program seen with some relevant comment(s). The program has been fully commented. Some identifier names used are appropriate. Some of the data structures used have meaningful names. The majority of identifiers used are appropriately named. Most of the data structures used have meaningful names. Suitable identifiers with names meaningful to their purpose have been used throughout. All of the data structures used have meaningful names. The solution is illogical. The solution contains parts that may be illogical. The program is in a logical order. The solution is inaccurate in many places. Solution contains few lines of code with errors that attempt to perform a task given in the scenario. The solution contains parts that are inaccurate. Solution contains lines of code with some errors that logically perform tasks given in the scenario. Ignore minor syntax errors. The solution is accurate. Solution logically performs all the tasks given in the scenario. Ignore minor syntax errors. The solution attempts at least one of the requirements. Solution contains lines of code that attempt at least one task given in the scenario. The solution meets most of the requirements. Solution contains lines of code that perform most tasks given in the scenario. The solution meets all the requirements given in the question. Solution performs all the tasks given in the scenario.