SST 2018 Prelim P1

SECONDARY 4 PRELIMINARY EXAMINATION COMPUTING Paper 1 Written 7155/01 29 August 2018 (Wednesday) 2 hours CANDIDATE NAME CLASS INDEX NUMBER READ THESE INSTRUCTIONS FIRST Do not turn over the page until you are told to do so. Write your name, class, and index number in the spaces provided above. Write in dark blue or black pen. You may use a pencil for any diagrams. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total number of marks for this paper is 80. This document consists of 18 printed pages. For Examiner’s Use 1 4 2 3 3 6 4 7 5 5 6 6 7 7 8 6 9 3 10 2 11 3 12 4 13 9 14 7 15 4 16 4 Total /80

Page 2 of 18 1 Computer data are represented as bytes. (i) Describe what is meant by a byte and how it is related to a bit. [1] (ii) The number of bytes in a gibibyte can be written as 2x. What is the value of x? [1] (iii) Convert the following amounts of data in the unit. 256 000 000 000 B (bytes) = _________________________ GB (gigabytes). 4 TB = ___________________________________B (bytes). [1] [1] 2 The terms 32-bit and 64-bit refer to the way a computer's central processing unit (CPU) handles memory addresses. Using byte-addressing, the processor can access one byte for each of the possible permutation of the 32 or 64 bits. (i) Dave thinks that a 64-bit computer handles twice as much random-access memory (RAM) than a 32-bit computer. State if Dave is correct. Explain. [2] (ii) A modern computer is likely to have 8 ____________ of RAM installed. (A) gigabytes (B) megabytes (C) kilobytes (D) bytes Choose the correct option: ________________ [1]

Page 3 of 18 [Turn over 3(a) Convert the hexadecimal number (2E7)16 to denary. Answer: _________________________________ [2] 3(b) Convert the binary number (10 1011 1101 0000 0100)2 to hexadecimal. Answer: _________________________________ [2] 3(c) Convert the denary number (3172)10 to hexadecimal. Answer: _________________________________ [2] 4 Study the following problem: A group of five friends booked a karaoke room for an evening and wanted to split the total bill equally among them. The rental fee for the room is $25 nett per hour and they spent $x on food and beverages (F&B). The cost on F&B is subjected to a service charge of 10% and a Goods and Services (GST) tax of 7%. A suggested input and output specification are included in the table below. Input Output hours : number of hours spent, rounded up to smallest integer greater or equal to itself. x: Amount, in Singapore dollars (SGD), spent on food and beverages. Cost_per_pax : Amount of money, in Singapore dollars (SGD), to be pa