O-LevelComputer ScienceAlgorithm design and problem-solving2210/21 · May/June 2017 · Q56 Marks

Describe the purpose of each statement in this algorithm. ``` FOR I <- 1 TO 300 INPUT Name [I] NEXT I ```

(a)Describe the purpose of each statement in this algorithm. ``` FOR I <- 1 TO 300 INPUT Name [I] NEXT I ```[2]
(b)Identify, using pseudocode, another loop structure that the algorithm in part (a) could have used.[1]
(c)Write an algorithm, using pseudocode, to input a number between 0 and 100 inclusive. The algorithm should prompt for the input and output an error message if the number is outside this range.[3]

Mark scheme

Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.

[2] Any two from:
- Loop with 300 repetitions (starting at 1) / Loops from 1 to 300
- Values input/stored (in consecutive/different locations) in an array (at position I)
- Increases the loop counter/I value by 1 (and returns to the start of the loop)
[1] Any one from:
- REPEAT (... UNTIL)
- WHILE (... DO ... ENDWHILE)
[1] Prompt and input number
[1] Checking the input number is between 0 and 100 - both limits
[1] Correct error message
Many correct algorithms. This is an example only.
OUTPUT "Enter a number between 0 and 100 "
INPUT Number
IF Number < 0 OR Number > 100
THEN
OUTPUT "The number you have entered is outside the specified range"
ENDIF

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