O-LevelComputer ScienceAlgorithm design and problem-solving2210/21 · May/June 2021 · Q56 Marks
The flowchart represents an algorithm. The algorithm will terminate if −1 is entered. [Figure 5.1]
- (a)Complete the trace table for the input data: 50, 75, 99, 28, 82, 150, -1, 672, 80[4]
- (b)Describe the purpose of the algorithm.[2]
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Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- [1] Row 1 (Value 50): Diff1 = 50, Diff2 = 0, OUTPUT = Accept: Extreme
- [1] Row 2 (Value 75): Diff1 = 25, Diff2 = 25, OUTPUT = Accept: Normal
- [1] Row 3 (Value 99): Diff1 = 1, Diff2 = 49, OUTPUT = Accept: Normal
- [1] Row 4 (Value 28): Diff1 = null, Diff2 = null, OUTPUT = Reject: Abnormal
- [1] Row 5 (Value 82): Diff1 = 18, Diff2 = 32, OUTPUT = Accept: Normal
- [1] Row 6 (Value 150): Diff1 = null, Diff2 = null, OUTPUT = Reject: Abnormal
- [1] Row 7 (Value -1): Termination (no output)
- [1] To output the type of test data
- [1] by performing a range check // by checking if numbers are within the range 50 and 100 (inclusive) (or not).
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