BVSS 2022 Prelim 4E Computing P2 MSv3

1 Marking scheme (4E Computing Prelim) Task 1 1 =ROUND(AVERAGE(C4:E4), 0) 2 1m for AVERAGE( ) 1m for ROUND( ) 2 ==MAX(F4:F12)-MIN(F4:F12) 1 3 =IF(OR(F4=MAX($F$4:$F$12), F4=LARGE($F$4:$F$12, 2)), "Favourite", "") OR =IF(F4=MAX($F$4:$F$12), "Favourite", IF(F4=LARGE($F$4:$F$12, 2), "Favourite", "") 3 1m for MAX( ) or LARGE( ) 1m for OR( ) 1m IF( ) 1m for MAX( ) or LARGE( ) 1m for IF( ) 1m for nested IF() 4 =(HLOOKUP(F4, $B$17:$E$19, 3, TRUE)+100)/100*B4 OR =(HLOOKUP(F4, $B$17:$E$19, 3, TRUE)/100 + 1)*B4 OR = HLOOKUP(F4, $B$17:$E$19, 3, TRUE)/100*B4 + B4 2 1m for HLOOK( ) 1m for correct calculation 5 Correct conditional formatting 2

2 Task 2 6 message = input("Enter a message: ") encrypted_m = "" for i in range(len(message)): if message[i] in "aeiou": encrypted_m = encrypted_m + message[i].upper() elif message[i] == " ": encrypted_m = encrypted_m + "&" else: encrypted_m = encrypted_m + chr(ord(message[i])+3) print("Encrypted message:", encrypted_m) 1m – check for vowel 1m – convert to upper case 1m – check for space 1m – convert to "&" and include else: for the rest of the cases

3 7 def decrypt(s): original_m = "" for i in range(len(s)): if s[i] in "AEIOU": original_m = original_m + s[i].lower() elif s[i] == "&": original_m = original_m + " " else: original_m = original_m + chr(ord(s[i])- 3) return original_m # main program print("Original message:", decrypt(encrypted_m)) 1m – initialise local variable 1m – check for vowel and convert to lower case 1m – check for "&" and convert to space 1m – convert to 3 characters in front 1m – return decrypted message 1m – call function correctly and print

4 Task 3 8 def correct_range(num, limit): return 0 <= num <= limit print("Time in 24-hour format are entered as 4 digits") valid = False while valid == False: time = input("Enter a time in 24-hour format: ") if len(time) != 4: print("Length of input must be 4") elif time.isdigit() == False: print("Input must be digits only") else: hour_int = int(time[:2]) minute_str = time[2:] if not correct_range(hour_int, 23): print("Hour must be in the range 0 to 23 inclusive") elif not correct_range(int(minute_str), 59): print("Minute must be in the range 0 to 59 inclusive") else: valid = True if correct_range(hour_int, 23) == False: if correct_range(int(minute_str), 59) == False:

5 if 0 <= hour_int <= 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 = str(new_hour) + ":" + minute_str + indicator print(converted_time)

6 Task 4 9 initialisation of 2 lists 1m while loop 1m FOR loop not acceptable 3 suitable input messages 1m appropriate error message 1m input name/mark and store in list 1m either name or mark while loop to validate marks correctly and re-prompt 1m update counter and total 1m update variable for loop continuation 1m correct output (count and average) 1m with appropriate message Max 9 m Accept if students use sum(), len() 9 initialisation of 2 lists 1m while loop 1m FOR loop not acceptable 3 suitable input messages 1m appropriate error message 1m input name/mark and store in list 1m either name or mark while loop to validate marks correctly and re-prompt 1m use of sum() and len() to find average 1m update variable for loop continuation 1m correct output (count and average) 1m with appropriate message Max 9 m

7 10 Test data – 2 marks: 1m – two types of test data 2m – three types of test data Output – 1 mark: 1m – correct output based on test data

8 11 loop management for checking 1m correct condition 1m store in list 1m correct output for 0 remedial 1m must not be followed by number of tutors appropriate output message 1m correct output for remedial 1m correct calculation for number of tutor 1m correct output for tutor 1m with appropriate message Max 8 m

9 Sample program Q8 name_list = [] mark_list = [] count = 0 total = 0 more_student = "y" while more_student == "y": name = input("Enter student name: ") name_list = name_list + [name] mark = int(input("Enter student mark: ")) while mark < 0 or mark > 100: print("Marks must be between 0 to 100 inclusive") mark = int(input("Re-enter student mark: ")) mark_list = mark_list + [mark] total = total + mark count = count + 1 more_student = input('Any more students? Enter "y" or "n": ').lower() average = total / count print("There are", count, "students") print("The average mark is", round(average, 1))

10 Sample program Q10 remedial_list = [] for i in range(len(mark_list)): if mark_list[i] < average: remedial_list = remedial_list + [name_list[i]] num_remedial = len(remedial_list) if num_remedial == 0: print("There are no students for remedial") else: print("Students identified for remedial class") for j in range(num_remedial): print(remedial_list[j]) num_tutor = num_remedial // 3 if num_remedial % 3 != 0: num_tutor = num_tutor + 1 print("Number of peer tutors needed:", num_tutor)