computing 2026 dhs prelim p1 qn

This document consists of 8 printed pages. Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 COMPUTING (Higher 2) 9569/01 Paper 1 Written 24 September 2026 3 hours READ THESE INSTRUCTIONS FIRST Write your name, index number and class on the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all the questions. Approved calculators are allowed. You are reminded of the need for good English and clear presentation in your answers. Please ask the invigilator if you require additional paper. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 100. [Turn over

2 DHS 2026 Year 6 H2 Computing Preliminary Examination Paper 1 1 A shop gives some customers a discount on goods totalling more than $20. The discounts are: • 5% for goods totalling more than $100 • 5% with a discount card • 10% with a discount card and goods totalling more than $100 (a) Copy and complete the decision table. [4] (b) Simplify your solution by removing redundancies in the final decision table. [2] (c) The simplified table produced in part (b) is used as design of a function in flowchart. The following identifier table shows the parameters to be passed to the function Discount. This function returns the discount amount as an integer. [3] Copy and complete the flowchart of function Discount. It begins with: Conditions goods totalling more than $20 Y Y Y Y N N N N goods totalling more than $100 Y Y N N Y Y N N have discount card Y N Y N Y N Y N Actions No discount 5% discount 10% discount Identifier Data type GoodsTotal INTEGER HasDiscountCard BOOLEAN FUNCTION Discount(GoodsTotal, HasDiscountCard)

3 DHS 2026 Year 6 H2 Computing Preliminary Examination Paper 1 2 (a) An IT company works on two types of projects; software projects and the installation of local area networks. Software projects are either bespoke software that is custom-made or off-the-shelf software. Projects have recorded: • project ID • start date • project leader Off-the-shelf software projects have recorded: • title • current state of beta testing o N – not started o O – ongoing o C – completed • anticipated retail price • sales forecast for first year of sales (units) Bespoke software projects have recorded: • customer name • agreed cost • agreed delivery date Software projects have recorded: • programming language used • current state of alpha testing o coded using the same three codes as for beta testing Networking projects have recorded: • client name • agreed cost This scenario is to be implemented using object-oriented programming. Copy and complete the class diagram using the classes: Bespoke, Network, OffTheShelf, Project, Software. Class diagram begins with: [8] Private: ProjectID : STRING Project [Turn over

4 DHS 2026 Year 6 H2 Computing Preliminary Examination Paper 1 (b) Terminology for object-oriented programming and design includes the following terms. Define the following terms with reference to part(a): (i) Class [1] (ii) Inheritance [1] (c) Part of the pseudocode for the object-oriented programming is shown below. CLASS Project PRIVATE ProjectID : STRING <statements> PROCEDURE set_ProjectID() <statements> ENDPROCEDURE FUNCTION get_ProjectID() <statements> ENDFUNCTION ENDCLASS CLASS Network INHERITS Project <statements> ENDCLASS // Main program … DECLARE ThisNetworkProject : Network <statements> Explain the following terms, with reference to the given pseudocode. (i) Instance [1] (ii) Method [1] (iii) Encapsulation [2] (d) A new software project is the stock control system. (i) Decomposition has been used to design the software project for stock control. Describe the term decomposition. [3] (ii) During the project development phase there were errors occurred when the programs were tested. Identify and describe any two types of errors that the programs may contain. [4]

5 DHS 2026 Year 6 H2 Computing Preliminary Examination Paper 1 3 The customer records are stored in two 1-D arrays. The key field, CustomerID, is in the range 1000 to 9999 store in a 1- D array. The rest of the details are stored in a 1- D array Record. A hashing algorithm has been designed to calculate each record’s address (index) using: Address ← CustomerID MOD 100 x MOD 100 returns a value which is the remainder when x is divided by 100. The record with this key is then stored at the calculated address. (a) Records with the following key fields are to be added to the file: 2003 3097 4007 6098 7008 Copy the following table and write the CustomerID where these records would be stored: Address CustomerID Record 00 01 02 03 04 05 06 07 08 96 97 98 99 [2] (b) (i) An additional record with key field 5097 is to be stored. State what will happen to the existing contents of the array. [1] (ii) Describe how the record handling software could prevent the outcome stated in part (b)(i). [2] (c) Explain the advantage a hash table search might have over a linear search and a binary search when searching for a specific record. Refer to time complexity in your answer. [3] [Turn over

6 DHS 2026 Year 6 H2 Computing Preliminary Examination Paper 1 4 Describe with a diagram how an insertion sort works. [3] 5 (a) Suppose a circular queue of capacity (n -1) elements is implemented with an array of n elements. Assume that the insertion and deletion operations are carried out using REAR and FRONT as array index variable respectively. Initially, REAR ← 0 and FRONT ← 0. Describe the conditions for detecting the queue is empty and full. [2] (b) For maintaining a log of user sessions in a secure trading platform, a queue data structure is used to process sessions in the order they arrive. If the queue is implemented with a circular array to optimise space, state the reason dequeuing the oldest session from a non-empty queue takes constant time O(1). [3] (c) Give two advantages of storing a stack in a linked list rather than in an array. [2] (d) (i) Draw a diagram to show the following members of a Computing class sorted into alphabetic order in a binary tree. You must use the names in the order given. FENG, TAN, BEN, ROSS, ASHLEY, WILLIAM, JAM [2] (ii) Describe an algorithm to insert a new member of the class into the correct position in the tree. [4] 6 A bank holds personal data about its customers and their financial data. (a) Describe the difference between security and integrity of data. [4] (b) Data integrity is required at the input stage. State two ways of maintaining data integrity at the input stage. Use examples to help explain your answer. [2] (c) Describe three security measures that the bank could implement to protect its electronic data. [3] (d) A manager downloads software from the Internet. Digital signature is part of the download to provide proof that the software is authentic. Describe the process for ensuring that the software is both authentic and has not been altered. [4] (e) Expla