computing 2026 acjc prelim p1 qn

ANGLO-CHINESE JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION Higher 2 COMPUTING 9569/01 Paper 1 Written 24 August 2026 3 hours READ THESE INSTRUCTIONS FIRST An answer booklet will be provided with the question paper. You should follow the instructions on the front cover of the answer booklet. If you need additional answer paper ask the invigilator for a continuation booklet. Answer all questions. Approved calculators are allowed. 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. __________________________________________________________________________________ This document consists of 9 printed pages and 1 blank page. [Turn Over

2 ANGLO-CHINESE JUNIOR COLLEGE 202 6 H2 COMPUTING 9569/01 1 A paper mill monitors its automated drying roll press during production to determine the machine's operational status. The monitoring system has three sensors each to check whether  the main roller power line is active,  a paper tear is detected on the line,  the temperature of dryer cylinder is at least 120 °C. If the main roller power line is active and both a paper tear is detected and the temperature of dryer cylinder is ≥ 120 °C, the system triggers an Emergency Line Shutdown. If the main roller power line is active and only one of these two faults occurs, the system issues an Urgent Maintenance Warning. Otherwise, the system maintains Normal Operations. (a) Copy and complete the decision table. Include all possible combinations and do not remove redundancies at this point. Rules Conditions Main roller power line is active Paper tear detected Temperature of dryer cylinder ≥ 120°C Actions Emergency Line Shutdown Urgent Maintenance Warning Normal Operations [4] (b) Draw a simplified decision table by removing redundancies from your answer in part (a). [2] (c) Write pseudo-code to input the status of the three sensors and output the appropriate system response from:  'Emergency Line Shutdown'  'Urgent Maintenance Warning'  'Normal Operations' Use the following identifiers in your pseudo-code: Identifier Name Description IsPowerActive Boolean indicating if main roller power is active IsPaperTear Boolean indicating if a paper tear is detected DryerTemp Temperature of dryer cylinder in degree Celsius [4]

3 ANGLO-CHINESE JUNIOR COLLEGE 202 6 H2 COMPUTING 9569/01 [Turn Over 2 Quicksort is an algorithm to arrange data items into ascending or descending order. The algorithm selects a pivot from the dataset, which is then used to divide the data into two subsets around the pivot. An enhanced version of the Quicksort algorithm selects the pivot using a median -of-three strategy for any partition with 3 or more elements. This method compares the first, middle and last elements of the current array segment and selects the median value as the pivot . When a segment has 2 or fewer elements remaining, the pivot value chosen is the first element of that segment. The contents of a given array with 15 elements are shown below: 42 18 85 31 67 4 99 53 12 76 29 61 90 38 45 (a) State the pivot value that will be selected for the first partition pass of the array. [1] (b) Use annotated diagrams to show how this enhanced Quicksort algorithm will sort the data in the array into ascending order. [4] (c) Suggest one theoretical advantage of using the median -of-three strategy over choosing the first or last element as the pivot. [1] (d) Explain why the worst-case time complexity of this enhanced Quicksort algorithm remains O(n2). [1] (e) State one sorting algorithm that has a better worst -case time complexity than Quicksort when sorting an unsorted array. [1] The Quicksort algorithm can also sort an array of text strings. (f) State one reason why Unicode is preferred over ASCII for character encoding when comparing and sorting multilingual data. [1] The contents of the given array, sorted in ascending order, are shown below: 4 12 18 29 31 38 42 45 53 61 67 76 85 90 99 (g) Explain why performing a linear search on a sorted array can be more efficient than on an unsorted array. [1] (h) A binary search algorithm could be used to search the sorted array. State the values that will be examined when searching for the value 80, which is not present in the array. [2]

4 ANGLO-CHINESE JUNIOR COLLEGE 202 6 H2 COMPUTING 9569/01 3 A university is designing an information management system to track different people on campus using Object-Oriented Programming (OOP). There are three categories of people: undergraduate student s, postgraduate student s, and professors. All people, in the class Person, have these features:  Attributes: name, ID_number  Methods: set_name, get_name, set_ID_number, get_ID_number, display_details Undergraduate students, in the class UStudent, have these additional features:  Attributes: GPA  Methods: set_GPA, display_GPA Postgraduate student s, in the class GStudent, have all the attributes and methods that undergraduate students have, and in addition, the following features:  Attributes: thesis_topic  Methods: set_thesis_topic, display_thesis_topic Professors, in the class Professor, have these additional features:  Attributes: salary  Methods: set_salary, display_salary (a) Draw a class diagram that shows the following as described above:  the superclass,  any subclasses,  inheritance relationships,  attributes,  appropriate methods. [8] (b) State one role of a constructor when a new object instance (such as Professor) is created. [1] (c) Explain why some attributes and methods in classes should be declared as private. [2] Polymorphism is applied when calling display details on various Person objects. (d) State one advantage of using polymorphism in this scenario. [1]

5 ANGLO-CHINESE JUNIOR COLLEGE 202 6 H2 COMPUTING 9569/01 [Turn Over 4 FreightGo is a smart logistics web platform that connects cross -border shoppers in Singapore with courier services for real-time parcel tracking. When a shopper visits the website (www.freightgo.sg) on their browser:  The browser performs a Domain Name System (DNS) lookup.  A secure HTTP (HTTPS) connection is established using TCP/IP with the company's central server.  The shopper logs into their account, where shipping addresses and delivery records are accessed and updated. (a) Describe the role of a DNS server when the user types www.freightgo.sg into their browser URL bar. [2] (b) Explain how TCP and IP function together at their respective layers of the TCP/IP suite to ensure that a tracking report downloaded from FreightGo reaches the client machine reliably and intact. [4] (c) State two risks to data security when transmitting tracking data and user information in plain text across an unsecured network, with elaboration. [4] Recently, FreightGo began to share customer tracking logs and browsing habits with third -party advertising brokers without explicit user consent. (d) Identify two ethical issues that may arise from this practice. [2] (e) Explain how this practice violates data protection principles under Singapore's Personal Data Protection Act (PDPA). [4]

6 ANGLO-CHINESE JUNIOR COLLEGE 202 6 H2 COMPUTING 9569/01 5 The flowchart below shows an algorithm for multiplying two integers, x and y. (a) Draw trace tables for the following inputs. (i) x = 5, y = 12 [3] (ii) x = 12, y = 5 [4] (b) Explain why the following steps in the flowchart are easy to carry out when x is expressed in binary notation. You may use the values of x in (a) as examples. (i) rem = x % 2 [2] (ii) x = x //