AQA GCSE COMPUTER SCIENCE Paper 1 Computational thinking and programming skills – C# MAY 2023

AQA GCSE COMPUTER SCIENCE Paper 1 Computational thinking and programming skills – C# Friday 19 May 2023 Afternoon Time allowed: 2 hours Materials • There are no additional materials required for this paper. • You must not use a calculator. Instructions • Use black ink or black ball-point pen. Use pencil only for drawing. • Answer all questions. • You must answer the questions in the spaces provided. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • Questions that require a coded solution must be answered in C#. • You should assume that all indexing in code starts at 0 unless stated otherwise. Information The total number of marks available for this paper is 90. Advice *Jun23 5251A01* IB/G/Jun23/E11 8525/1A Answer all questions. box Figure 1 shows an algorithm, represented using pseudo-code, which assigns a different value to four variables. Figure 1 country  'United States of America' state  'California' city  'San Francisco' landmark  'Alcatraz Island' . Define the term algorithm. [2 marks] . The variable x is assigned a value using the statement: x  LEN(state) Using Figure 1, what is the value of x? Shade one lozenge. [1 mark] A 1 B 5 C 10 D 12 . What is the result of concatenating the contents of the variables city and landmark in Figure 1? Shade one lozenge. [1 mark] box A San Francisco Alcatraz Island B San Francisco,Alcatraz Island C San Francisco, Alcatraz Island D San FranciscoAlcatraz Island . The subroutine SUBSTRING extracts characters from a given string. For example, SUBSTRING(3, 5, 'Computing') would return put The variable y is assigned a value using the statement: y  SUBSTRING(4, 7, landmark) Using Figure 1, what is the value of y? Shade one lozenge. [1 mark] A Alca B Atra C land D traz Question 1 continues on the next page Turn over ► Figure 1 has been included again below. Figure 1 country  'United States of America' state  'California' city  'San Francisco' landmark  'Alcatraz Island' . The subroutine POSITION finds the first position of a character in a string. For example, POSITION('Computing', 'p') would return 3 The variable z is assigned a value using the statement: z  POSITION(landmark, 't') Using Figure 1, what value is assigned to z? Shade one lozenge. [1 mark] box A –1 B 3 C 4 D 5 Turn over for the next question DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED box Turn over ► Figure 2 shows an algorithm that uses integer division which has been represented using pseudo-code. • Line numbers are included but are not part of the algorithm. Figure 2 1 again  True 2 WHILE again = True 3 a  USERINPUT 4 IF a > 0 THEN 5 counter  0 6 WHILE a > 0 7 a  a DIV 3 8 counter  counter + 1 9 ENDWHILE 10 ELSE 11 again  False 12 ENDIF 13 OUTPUT a 14 ENDWHILE Integer division is the number of times one integer divides into another, with the remainder ignored. For example: • 14 DIV 5 evaluates to 2 • 25 DIV 3 evaluates to 8 box . Where is iteration first used in the algorithm in Figure 2? Shade one lozenge. [1 mark] A Line number 2 B Line number 4 C Line number 6 D Line number 11 . In the algorithm in Figure 2, what will be output when the user input is 10? Shade one lozenge. [1 mark] box A 0 B 1 C 2 D 4 . In the algorithm in Figure 2, what is the largest possible value of the variable counter when the user input is 36? Shade one lozenge. [1 mark] A 0 B 2 C 4 D 5 Explain one advantage of the structured approach to programming. [2 marks] *07* Turn over ► Figure 3 shows a program written in C# that calculates the area of a rectangle or the volume of a box from the user inputs. Figure 3 box public static int calculate(int width, int length, int height) { if (height == -1) { return width * length; } else { return width * length * height; } } public static void Main() { int numOne, numTwo, numThree, answer; Console.Write("Enter width: "); numOne = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter length: "); numTwo = Convert.ToInt32(Console.ReadLine()); Console.Write("Enter height, -1 to ignore: "); numThree = Convert.ToInt32(Console.ReadLine()); answer = calculate(numOne, numTwo, numThree); if (numThree == -1) { Console.WriteLine($"Area {answer}"); } else { Console.WriteLine($"Volume {answer}"); } } . Complete the trace table using the program in Figure 3. [3 marks] numOne numTwo numThree Final output 5 6 –1 10 4 0 3 5 10 . Describe one way that the program in Figure 3 could be made more robust. [1 mark] box Turn over for the next question Turn over ► Figure 4 shows an algorithm presented as a flowchart. Figure 4 Complete the trace table for the algorithm in Figure 4. You may not need to use all the rows in the table. [3 marks] box Turn over for the next question DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED box Turn over ► Figure 5 shows an algorithm represented using pseudo-code. The algorithm is for a simple authentication routine. The pseudo-code uses a subroutine getPassword to check a username: • If the username exists, the subroutine returns the password stored for that user. • If the username does not exist, the subroutine returns an empty string. Parts of the algorithm are missing and have been replaced with the labels to . Figure 5 box login  False REPEAT username  '' WHILE username = '' OUTPUT 'Enter username: ' username  ENDWHILE password  '' WHILE password = '' OUTPUT 'Enter password: ' password  USERINPUT ENDWHILE storedPassword  getPassword( ) IF storedPassword = THEN OUTPUT ' ' ELSE IF password = storedPassword THEN login  True ELSE OUTPUT 'Try again.' ENDIF ENDIF UNTIL login = True OUTPUT 'You are now logged in.' Figure 6 -1 OUTPUT 0 username True SUBROUTINE 1 User not found '' USERINPUT password Wrong password State the items from Figure 6 that should be written in place of the labels in the algorithm in Figure 5. box You will not need to use all the items in Figure 6. [4 marks] Turn over for the next question Turn over ► A theme park charges £15 per person for a daily ticket. If there are six or more people in a group, the group is given a £5 discount. Write a C# program to calculate the total charge for a group of people visiting the theme park. The program must: • get the user to enter the number of people in a group • calculate the total charge by: o charging £15 per person o reducing the total charge by £5 if there are six or more people • output the total charge. You should use meaningful variable name(s) and C# syntax in your answer. box The answer grid below contains vertical lines to help you indent your code. [6 marks]