Computer Science · May / June 2021 · Paper 22 · Question 1
0478
As printed in the paper
The question as text
All variables, constants and other identifiers must have meaningful names.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
1(a)[3]
Array
TrainUpPassengers // TrainUpPassengers[]
Data type
Integer/int
Use
storing the number of passengers on the train journeys up
Many correct answers, this is an example.
1(b)[6]
One mark for description, one mark for normal data and one mark for erroneous data for two checks
Validation check (type check) to check that the number entered is a whole number / integer
Normal data
34
Erroneous data
two // 1.5
Validation check (range check) to check that the value of the number entered is between 1 and 80 / 480 inclusive Normal data
34
Erroneous data
99 // 500
Validation check (presence check) to check that a value has been entered
Normal data
34 // any data entered
Erroneous data
“” // blank // no data entered
Validation check (length check) to check that a value has 3 digits or fewer // between 1 and 3 digits
Normal data
345
Erroneous data
3456
Many correct answers, the data are examples only.
1(c)[6]
Any six from:
MP1
Input number of tickets
MP2
Input train up mountain and train down mountain
MP3
Suitable prompts seen for inputs that are included
MP4
Check that tickets are available on selected train(s)
MP5
If available calculate price of tickets …
MP6
… calculation includes discount if required
MP7
Update total passengers / seats available for a train
MP8
Update total passengers / seats available for up train and down train
MP9
Update total cost for a train
MP10 Update total cost for up train and down train
Example answers
OUTPUT "How many tickets"
INPUT NoTickets
OUTPUT "Which Train up the mountain? 1, 2, 3 or 4"
INPUT UpNumber
OUTPUT "Which Train down the mountain? 1, 2, 3 or 4"
INPUT DownNumber
IF (DownNumber = 4 AND TrainUp[UpNumber] + NoTickets <= 480 AND TrainDown[DownNumber] + NoTickets <= 640) OR (TrainUp[UpNumber] + NoTickets <= 480 AND TrainDown[DownNumber] + NoTickets <= 480)
THEN
Cost ← (NoTickets – NoTickets DIV 10) * 50
TrainUp[UpNumber] ← TrainUp[UpNumber] + NoTickets
TrainDown[DownNumber] ← TrainUp[DownNumber] + NoTickets
TrainUpTotal[UpNumber] ← TrainUpTotal[UpNumber] + Cost / 2
TrainDownTotal[DownNumber] ← TrainDownTotal[DownNumber] + Cost / 2
ENDIF
START
OUTPUT "Tickets"
INPUT Tickets
OUTPUT "Up Train"
INPUT UpNo
OUTPUT "Down Train"
Yes
INPUT DownNo
No
Is Tickets <=
UpTickets[UpNo] AND
Tickets <=
DownTickets[DownNo]?
Yes
Cost ← (NoTickets – NoTickets DIV 10) * 50
TrainUp[UpNo] ← TrainUp[UpNo] + NoTickets
TrainDown[DownNo] ← TrainUp[DownNo] + NoTickets
TrainUpTotal[UpNo] ← TrainUpTotal[UpNo] + Cost / 2
TrainDownTotal[DownNo] ← TrainDownTotal[DownNo] + Cost / 2
END
1(d)[5]
Explanation
Any five from:
MP1
How the program displayed the number of passengers for a journey ...
MP2
… how completed for all trains
MP3
How the program displayed the amount of money taken for a journey …
MP4
… how completed for all trains
MP5
How the program calculated the total number of passengers
MP6
How the program calculated the total money taken
MP7
How the program attempted to select the train journey with the most passengers
MP8
How the program attempted to dealt with more than one train being the most popular
MP9
How the program displayed the results with suitable messages
Programming statements must be given with each explanation.
Section B
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