BVSS 2022 Prelim 4E Computing P2v3

Bukit View Secondary School Secondary Four Express Preliminary Examination 2022 BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY SCHOOL BUKIT VIEW SECONDARY CANDIDATE NAME CLASS INDEX NUMBER COMPUTING 7155/2 Paper 2 (Lab-based) 13 September 2022 2 hour 30 minutes Additional Materials: Electronic version of CAFE.xlsx data file Electronic version of ENCRYPT.py file Electronic version of TIME.py file Insert Quick Reference Glossary READ THESE INSTRUCTIONS FIRST Write your candidate name, class and index number in the spaces provided at the top of this page. Write in dark blue or black pen. Answer all questions. All tasks must be done in the computer laboratory. You are not allowed to bring in or take out any pieces of work or materials on paper or electronic media or in any other form. Programs are to be written in Python. Save your work using the file name given in the question as and when necessary. 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 50. For Examiner’s use Marks 50 Setter: Mrs Leong Wee Choo Parent’s Signature: ________________

2 ________________________________________________________________________ This question paper consists of 9 printed pages, 1 blank page and 1 insert. Task 1 Amy runs a cafe. Due to the increase in prices of ingredients and utilities, she has to adjust the prices of her food items. To help her decide on the percentage of increase, she decides to use a spreadsheet to keep track of her sales from Friday to Sunday. You are required to finish setting up the spreadsheet for the required details of her business. Open the file CAFE.xlsx. You will see the following data. Cells C4 to E12 show the number of each item sold from Friday to Sunday. Save the file as MYCAFE_2022_<your name>_<index number>.xlsx 1 In the Average sold column, enter a formula that uses a function to calculate the average number of items sold. The average number must be rounded off to the nearest integer. [2] 2 In cell C14, enter a formula to calculate the range of average sold. [1]

3 3 In the Status column, enter a formula that uses functions to find the top two food items based on average sold and display the text Favourite for these food items. The other cells in the column must be empty. [3] 4 Use an appropriate function to sea rch for the Increment (%) in the Percentage Increase table, and use it to complete the New Price column. [2] 5 In cells A4 to H12, use a conditional formatting tool to fill the row blue if the first character of the food item is greater than "P". [2] Save and close your file.

4 Task 2 The following program reads in a message and prints out the encrypted message by replacing each character with the character 3 positions behind it based on the ASCII table. You can assume the message is in lower case. message = input("Enter a message: ") encrypted_m = "" for i in range(len(message)): encrypted_m = encrypted_m + chr(ord(message[i])+3) print("Encrypted message:", encrypted_m) Open the file ENCRYPT.py Save the file as MYENCRYPT_2022_<your name>_<index number>.py 6 Edit the program to implement the following changes to the encryption algorithm: ● replace lower case vowel ("a", "e", "i", "o", "u") with the same vowel in upper case instead ● replace space with "&" instead [4] Save your program. 7 Write a function decrypt(s) which takes in the encrypted message and returns the original message. [5] Call the function to take in the encrypted message and print out the original message. [1] Save your program.

5 Task 3 The program on the next page asks the user to enter time in 24 -hour format (HHMM), validates the input and outputs the time in 12-hour format. The program displays a suitable message to indicate why the input is invalid and repeatedly takes in input until the user enters a valid time. A time is invalid if it: ● does not contain 4 digits only ● hour (HH) is not within the range 0 to 23 inclusive ● minute (MM) is not within the range 0 to 59 inclusive The program calls the function correct_range() to validate hour and minute. Function correct_range(num, limit) takes in two integers as parameters. It returns a boolean value True if num is within the range of 0 and limit (inclusive); otherwise it returns False. If the time is valid, the program prints the time in 12-hour format. Some correct sample output is shown here: ● 12:00AM if the input is 0000 ● 9:36AM if the input is 0936 ● 12:00PM if the input is 1200 ● 11:33PM if the input is 2333 There are several syntax errors and logic errors in the program.

6 def correct_range(num, limit): return 0 <= num < limit print("Time in 24-hour format should be entered as 4 digits") valid = False while valid == True: time = input("Enter a time in 24-hour format: ") if len(time) = 4: print("Length of input must be 4") elif time.hasdigit() == False: print("Input must be digits only") else: hour_int = int(time[:2]) minute_str = time[2:] if not correct_range(hour_int): print("Hour must be in the range 0 to 23 inclusive") elif correct_range(int(minute_str), 59): print("Minute must be in the range 0 to 59 inclusive") else: valid = False if 0 <= minute_str <= 11: indicator = "AM" else: indicator = "PM" new_hour = hour_int if hour_int == 0: new_hour = hour_int + 12 elif hour_int >= 13: new_hour = hour_int + 12 converted_time = new_hour + ":" + minute_str + indicator print(converted_time)

7 Open the file TIME.py Save the file as MYTIME_2022_<your name>_<index number>.py 8 Identify and correct the errors in the program so that it works correctly according to the requirements given. Save your program. [10]

8 Task 4 You have been asked to write a program for a teacher to enter the students' names and their respective test marks. The test marks are whole numbers only. The program must: ● allow the user to enter student's name and mark and store the input in 2 different lists. The program does not need to validate student's name. However, it must ask for another mark each time the user enters a mark that is not between 0 and 100 inclusive. ● ask the user if there are any more students' details to be input. The program does not n