A-LevelMathematicsProbability and statistics9709/62 · May/June 2022 · Q14 Marks
A javelin thrower noted the lengths of a random sample of 50 of her throws. The sample mean was 72.3 m and an unbiased estimate of the population variance was 64.3 m².
- (a)Find a 92% confidence interval for the population mean length of throws by this athlete.[3]
- (b)A discus thrower wishes to calculate a 92% confidence interval for the population mean length of his throws. He bases his calculation on his first 50 throws in a week. Comment on this method.[1]
Mark scheme
Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.
- [M1] Expression of correct form (allow only one side for M1). Must be a z value
- [B1] Accept 1.75 if nothing better seen
- [A1] Allow without units Must be an interval
- [B1] Need 'random' or 'not representative/biased because...' OE
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