ZHSS 2020 Computing P1

Setter: Mr. Calvin Heng Vetter: Mr. Low Kee Ley This question paper consists of 14 printed pages including this cover page. ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2020 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number COMPUTING 7155/01 Paper 1 18 September 2020 2 hours Additional Materials: NIL READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all the questions. Write your answers in this question booklet. Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place in the case of angles in degrees, unless a different level of accuracy is specified in the question. The use of a scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. At the end of the presentation, fasten all your work securely together. 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 80. For Examiner’s Use:

2 1 (a) Convert 8 bits into GB. [1] (b) Convert 64 Terabytes into KB. [1] 2 Draw a line to match the terms to its correct description. Terms Description DoS attack l Cookie l l A small piece of data used by websites to store personal information on a user’s web browser. Encryption l l Hidden program that secretly collects personal information. Phishing l l Flooding network with useless traffic, making the network slow or inaccessible. Software piracy l l Sending fake or spoof emails. Spyware l [4]

3 3 Fill in the blanks with the helping words. ALU APPLICATION RAM CPU ROM UTILITY (a) ____________________ is high speed, volatile memory. (b) The accumulator stores intermediate results of calculations in the __________ . (c) Antivirus software is an example of a software. (d) ____________________ tells the CPU how to Boot Up. [4] 4 Fiona is a graphic designer for a publishing company. The image editing software that she uses represents each unique colour as a six digit hexadecimal code. (a) As a power of 16, how many possible unique colours could Fiona use? (workings must be shown clearly) [2] (b) Explain one benefit to programmers of using hex codes to represent the different colours. [2]

4 5 The use of technology has impacted our lives in many areas. Describe two advantages and two disadvantages of the impact of technology on healthcare. Advantage 1 Advantage 2 Disadvantage 1 Disadvantage 2 [4]

5 6 Access to a computer system is becoming more sophisticated. One area of major development is in user authentication. (a) Describe what is authentication and how it works? [2] (b) One way to conduct authentication is to use two-factor authentication. Explain how two-factor authentication works using a one-time-password (OTP) on the users’ mobile phone. [2] (c) Suggest another way to implement two-factor authentication. [2]

6 7 Besides optical technology storage devices, name two other types of external storage technologies found in a computer system. List their corresponding example and describe each of them in terms of their advantage and disadvantage. Type 1 : ______________________________ Example: _____________________________ Description [3] Type 2 : ______________________________ Example: _____________________________ Description: [3]

7 8 Study the Boolean statement: Q = (NOT A AND B) OR (NOT B and C) (a) Complete the truth table for the Boolean statement above. A B C Working Space Q 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [2] (b) Draw a logic circuit for the Boolean statement above. [4] A B C Q

8 9 Dr Heng records a patient’s temperature once an hour for six hours. Any time the temperature is > 37C, an incidence of fever is recorded. The average of all temperatures taken is calculated at the end. (a) Before you complete the trace table, calculate the average temperature (to one decimal place) using the following test data: 36, 36, 38.5, 37, 38, 36 Expected result = ___________ (b) Complete the trace table using the temperatures above. Line Pseudocode 010 temp ß 0 020 fever ß 0 030 total ß 0 040 hour ß 1 050 WHILE hour < 7 060 OUTPUT “Enter Temp: “ 070 temp ß USERINPUT 080 IF temp > 37 THEN 090 fever ß fever + 1 100 END IF 110 total = total + temp 120 hour = hour + 1 130 ENDWHILE 140 average ß ROUND(total/hour, 1) # round to 1 decimal place 150 OUTPUT “Average Temp: “, average 160 OUTPUT “Fever Incidents: “, fever temp fever total hour average OUTPUT [5] (c) Is the algorithm correct? If not, write your change to the pseudo-code below so that it gives the correct results. [1]

9 10 The spreadsheet below shows the information of a shopping list. (a) The spreadsheet above contains: ____ rows and ____ columns. [1] (b) The most likely function used in cell E7 is: [1] (c) A formula =(C4*D4)*(1-E4/100) is entered into cell F4 to calculate the total price for 4 packs of Dental Floss. The formula is copied to complete column F. Write down the formula in cell F7: [1] (d) GST is charged at 7% of the Sub-Total. Write down the formula in cell F11: [1] (e) Why does the cell F10 show “#######”? [1] (f) Customers who spend a sub-total of $1,000 and above qualify for a lucky draw. Write down the function in cell B12 to display “*” if the customer qualifies or “-“ otherwise. [1]

10 11 In a computer game, a character’s status depends on three variables: hunger, hydration and comfort. If any of the three conditions are met then the character dies, otherwise they are alive. Conditions: • Any of the variables are equal to 0. • Any two of the variables are less than 20. • All three of the variables are less than 40. There are three errors in the Python code. Locate the errors and state the correct code. Line Code 100 alive == True 110 If hunger == 0 or hydration == 0 or comfort == 0: 120 alive = False 130 elif (hunger < 20 and hydration < 20) or (hunger < 20 and 140 comfort < 20) and (hydration < 20 or comfort < 20): 150 alive = False 160 elif hunger < 40 or hydration < 40 or comfort < 40: 170 alive = False 180 else: 190 alive = True Note: Line 140 continues from Line 130 (a) Error 1: _________________________________________________ Correction 1: ____________________________________________ (b) Error 2: _________________________________________________ Correction 2: ____________________________________________ (c) Error 3: _________________________________________________ Correction 3: ____________________________________________ [6] (d) The variable alive is of type ____________________. [1] (e) State another Boolean operator besides the two used in this program: __________________. [1]