Cambridge IGCSE Computer Science (9-1) 0984 — 2020 May/June Paper 2 · Variant 2

Cambridge IGCSE™(9–1) COMPUTER SCIENCE 0984/22 Paper 2 Problem-solving and Programming May/June 2020 1 hour 45 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Do not attempt Tasks 1, 2 and 3 in the copy of the pre-release material on page 2; these are for information only. ● 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 50. ● 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. This document has 16 pages. Blank pages are indicated. * 7 0 9 9 2 9 8 6 7 2 * DC (JP) 198774 © UCLES 2020 [Turn over

2 0984/22/M/J/20 © UCLES 2020 Section A You are advised to spend no longer than 40 minutes answering this section. Here is a copy of the pre-release material. DO NOT attempt Tasks 1, 2 and 3 now. Use the pre-release material and your experience from attempting the tasks before the examination to answer Question 1. Pre-release material A car park payment system allows customers to select the number of hours to leave their car in the car park. The customer will get a discount if they enter their frequent parking number correctly. The system calculates and displays the amount the customer must pay. The price of parking, the number of hours the customer can enter, and any discount depend upon the day of the week and the arrival time. The number of hours entered is a whole number. The price per hour is calculated using the price in force at the arrival time. No parking is allowed between Midnight and 08:00. Day of the week Arrival time From 08:00 to 15:59 From 16:00 to Midnight Max stay in hours Price per hour Hours Price Sunday 8 2.00 Up to Midnight 2.00 Monday 2 10.00 Up to Midnight 2.00 Tuesday 2 10.00 Up to Midnight 2.00 Wednesday 2 10.00 Up to Midnight 2.00 Thursday 2 10.00 Up to Midnight 2.00 Friday 2 10.00 Up to Midnight 2.00 Saturday 4 3.00 Up to Midnight 2.00 A frequent parking number can be entered for discounted parking. This number consists of 4 digits and a check digit that is calculated using a modulo 11 check digit calculation. A discount of 50% is available for arrival times from 16:00 to Midnight; the discount is 10% at all other arrival times. Write and test a program or programs to simulate the car park payment system. • Your program or programs must include appropriate prompts for the entry of data; data must be validated on entry. • Error messages and other output need to be set out clearly and understandably. • All variables, constants and other identifiers must have meaningful names. You will need to complete these three tasks. Each task must be fully tested. Task 1 – Calculating the price to park. A customer inputs the day, the hour of arrival excluding minutes (for example 15:45 would be 15), the number of hours to leave their car, and a frequent parking number if available. If the frequent parking number has an incorrect check digit, then no discount can be applied. The price to park, based on the day, the hour of arrival, the number of hours of parking required and any discount available, is calculated and displayed. Task 2 – Keeping a total of the payments. Extend Task 1 to keep a daily total of payments made for parking. The daily total is zeroed at the start of the day. For the simulation, each customer inputs the amount paid, this must be greater than or equal to the amount displayed. There is no change given so the amount input may exceed the amount displayed. Each customer payment is added to the daily total, and this total is displayed at the end of the day. Task 3 – Making payments fairer. Customers have complained that sometimes they are being charged too much if they arrive before 16:00 and depart after 16:00. Extend Task 1 to calculate the price before 16:00, then add the evening charge. For example, a customer arriving at 14:45 on a Sunday and parking for five hours was previously charged 10.00 and would now be charged 6.00

3 0984/22/M/J/20 © UCLES 2020 [Turn over 1 All variables, constants and other identifiers must have meaningful names. (a) Identify two variables that you could have used for Task 1. Give the data type and state the use of each variable. Variable 1 … Data type … Use … … Variable 2 … Data type … Use … … [4] (b) Data input by a customer for Task 1 includes the day and the hour of arrival. Identify one suitable validation check for each input and justify your choice. Your validation checks must be different. Day of arrival – validation check … … Justification … … … … Hour of arrival – validation check … … Justification … … … … [4]

4 0984/22/M/J/20 © UCLES 2020 (c) Explain how your program for Task 1 ensured that the frequent parking number entered by the customer had a valid check digit. … … … … … … … … … … … … … … [4] (d) Write an algorithm for part of Task 2 that simulates customer payment and calculating total payments using either pseudocode, programming statements or a flowchart. Assume that Task 1 has been completed. … … … … … … … … … … …

5 0984/22/M/J/20 © UCLES 2020 [Turn over … … … … … … … … … … … … … … … … … … … … … … … … … … … … [4]

6 0984/22/M/J/20 © UCLES 2020 (e) Explain how your program completed Task 3. Assume that Task 2 has been completed. Any programming statements used in your answer must be fully explained. … … … … … … … … … … … … … … … … … [4]

7 0984/22/M/J/20 © UCLES 2020 [Turn over Section B 2 Most programming languages include basic data types. Ahmad is describing the basic data types he has used. State the data type that Ahmad is describing in each sentence. Choose the data type from this list of programming terms. Array Boolean Char Constant Function Integer Iteration Procedure Real String Variable A number with a fractional part that can be positive or negative and used in calculations Data type … A whole number that can be positive, negative or zero and used in calculations Data type … A single number, symbol or letter Data type … A sequence of characters Data type … A data type with two values, True or False Data type … [5]

8 0984/22/M/J/20 © UCLES 2020 3 (a) An algorithm has been written in pseudocode to input the names and marks of 35 students. The algorithm stores the names and marks in two arrays Name[ ] and Mark[ ]. The highest mark awarded is found and the number of students with that mark is counted. Both of these values are output. 01 HighestMark ← 100 02 HighestMarkStudents ← 0 03 FOR Count ← 1 TO 35 04 OUTPUT "Please enter student name" 05 INPUT Name[Count] 06 OUTPUT "Please enter student mark" 07 INPUT Mark[Counter] 08 IF Mark[Count] = HighestMark 09 THEN 10 HighestMarkStudents ← HighestMarkStudents – 1 11 ENDIF 12 IF Mark[Count] > HighestMark 13 THEN 14 Mark[Count] ← HighestMark 15 HighestMarkStudents ← 1 16 ENDIF 17 NEXT Count 18 OUTPUT "There are ", HighestMarkStudents," with the highest mark of ", HighestMark Give line numbers where the four errors are to be found in the pseudocode. Suggest a correction for each error. Error 1 line number … Correction … … Error 2 line number … Correction … … Error 3 line number … Correction … … Error 4 line number … Correction … … [4]

9 0984/22/M/J/20 © UCLES 2020 [Turn over (b) Explain how you could extend the algorithm to also find the lowest mark awarded, count the number of students with that mark, and output both these values. … … … … … … … … … … … … … … … … … … … … … … … … … … … [6]

10 0984/22/M/J/20 © UCLES 2020 4 This flowchart inputs the points won and the points lost when playing a game. The difference between the points won and lost is calculated and depending on the result the player can: move up to the next level, stay at the same level, or move down to the previous level. The flowchart finishes when the input for points won is –1. START INPUT PointsWon, PointsLost END Yes Yes Yes No No No OUTPUT "Keep on trying" OUTPUT "Sorry move down" Difference PointsWon - PointsLost IS PointsWon = –1 ? IS Difference > = 1000 ? IS Difference < 0 ? OUTPUT "Well done move up"

11 0984/22/M/J/20 © UCLES 2020 [Turn over (a) Complete a trace table for this set of input data: 5000, 4474, 6055, 2000, 7900, 9800, 3000, 2150, –1, 6700, 7615 PointsWon PointsLost Difference OUTPUT [3] (b) The flowchart needs to be changed. When the difference is more than 5000 the output message is ‘Fantastic leap up two levels’. Describe the changes that will need to be made to the flowchart. … … … … … … … … [3]

12 0984/22/M/J/20 © UCLES 2020 5 Arrays are data structures used in programming. Explain what is meant by the terms dimension and index in an array. Use examples of arrays in your explanations. Dimension … … … … … Index … … … … … [3]

13 0984/22/M/J/20 © UCLES 2020 6 A database table, JUICE, is used to keep a record of cartons of fresh fruit juice available for sale. Juice code Fruit 1 Fruit 2 Size Volume (ml) Stock level LMO10 Mango Orange Large 1000 18 MOO05 Orange Orange Medium 500 8 SAM02 Apple Mango Small 200 25 SAA02 Apple Apple Small 200 50 SPP02 Pineapple Pineapple Small 200 10 MMM05 Mango Mango Medium 500 12 LMM10 Mango Mango Large 1000 5 MGG05 Guava Guava Medium 500 5 SMO02 Mango Orange Small 200 7 MOP05 Orange Pineapple Medium 500 12 LAA10 Apple Apple Large 1000 32 SGO02 Guava Orange Small 200 10 LPP10 Pineapple Pineapple Large 1000 3 LOO10 Orange Orange Large 1000 25 SOO02 Orange Orange Small 200 40 (a) Identify a suitable field to use as the primary key. State a reason for your choice. Field … Reason … … [2] (b) Complete the query-by-example grid to display only the stock level and size of all cartons containing only apple juice. Field: Table: Sort: Show: Criteria: or: [4]

14 0984/22/M/J/20 © UCLES 2020 BLANK PAGE

15 0984/22/M/J/20 © UCLES 2020 BLANK PAGE

16 0984/22/M/J/20 © UCLES 2020 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 the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge. BLANK PAGE

This document consists of 8 printed pages. © UCLES 2020 [Turn over Cambridge IGCSE™ (9–1) COMPUTER SCIENCE 0984/22 Paper 2 May/June 2020 MARK SCHEME Maximum Mark: 50 Published Students did not sit exam papers in the June 2020 series due to the Covid-19 global pandemic. This mark scheme is published to support teachers and students and should be read together with the question paper. It shows the requirements of the exam. The answer column of the mark scheme shows the proposed basis on which Examiners would award marks for this exam. Where appropriate, this column also provides the most likely acceptable alternative responses expected from students. Examiners usually review the mark scheme after they have seen student responses and update the mark scheme if appropriate. In the June series, Examiners were unable to consider the acceptability of alternative responses, as there were no student responses to consider. Mark schemes should usually be read together with the Principal Examiner Report for Teachers. However, because students did not sit exam papers, there is no Principal Examiner Report for Teachers for the June 2020 series. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the June 2020 series for most Cambridge IGCSE™ and Cambridge International A & AS Level components, and some Cambridge O Level components.

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 2 of 8 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.

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 3 of 8 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.

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 4 of 8 Section A Question Answer Marks 1(a) For two variables One mark for identification of a variable with a suitable data type and one mark for its use Variable hourArrived Data type integer Use to calculate the price based on the number of hours parking Variable priceToPay Data type real Use store result of price calculation Many correct answers, these are examples only. 4 1(b) For each validation check One mark for identification of a check and one mark for the justification Day Check presence check Justification need to enter day to be able to calculate price Hour Check range check Justification need to check hour is between 8 and 23 Many correct answers, these are examples only. 4

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 5 of 8 Question Answer Marks 1(c) Any four from: • All 5 digits input • Each of the first 4 digits is multiplied by a weight based on its position • Specific method of individualising the digits described • Added together divided by 11 • Remainder used to calculate correct 5th digit • Checked against 5th digit input • If the same, then valid 4 1(d) Any four from: • Input amount • Check amount greater than or equal to the price to pay … • … True – add amount to daily total • … False – ask for payment to be re-entered • … Until valid amount input Sample answer PRINT "Please Enter Payment" INPUT amount WHILE amount < priceToPay DO PRINT "Insufficient payment, please enter new Payment" INPUT amount ENDWHILE totalPayment ← totalPayment + amount 4 1(e) Explanation Any four from: • Add number of hours selected to arrival hour • Check if this is greater than 16 • True – calculate price up to 16 … • … using current price in force • … and add in evening charge • False – calculate price as usual Programming statements can be used but must be explained. 4

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 6 of 8 Section B Question Answer Marks 2 Real Integer Char/String String Boolean 5 Question Answer Marks 3(a) One mark for error and correction Line 1 HighestMark ← 0 Line 7 INPUT Mark[Count] Line 10 HighestMarkStudents ← HighestMarkStudents + 1 Line 14 HighestMark ← Mark[Count] 4 3(b) Any six from: Add variable LowestMark … … Set this to a high value for example 100 Add variable LowestMarkStudents … … Set this to zero Check if Mark[Count] = LowestMark … … True – add 1 to LowestMarkStudents Check if Mark[Count] < LowestMark … … True – set LowestMarkStudenta to 1 and set LowestMark to Mark[Count] Add extra output statement 6

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 7 of 8 Question Answer Marks 4(a) One mark for correct input (PointsWon and PointsLost) One mark for correct calculations (Difference) One mark for correct output PointsWon PointsLost Difference OUTPUT 5000 4474 526 Keep on trying 6055 2000 4055 Well done move up 7900 9800 -1900 Sorry move down 3000 2150 850 Keep on trying -1 6700 3 4(b) Any three from: • Add extra decision box … • … before checking for difference greater than or equal to 1000 // change Is difference >= 1000 to >= 1000 and <= 5000 • Check for difference greater than 5000 • Add extra Output ‘Fantastic leap up two levels’… • … before flowline returns to input 3

0984/22 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 8 of 8 Question Answer Marks 5 One mark for explanation of dimension One mark for explanation of index One mark for inclusion of an example The dimension is the number of indexes required to access an element. The index is the position of the element in an array For example A[25] is the 25th element of a one-dimensional array. 3 Question Answer Marks 6(a) One mark for field and one mark for reason Field Juice code Reason only unique identifier 2 6(b) Field: Fruit 1 Fruit 2 Size Stock level Table: JUICE JUICE JUICE JUICE Sort: Show:     Criteria: ="Apple" ="Apple" or: One mark for each correct column 4