A-LevelMathematicsProbability and statistics9709/52 · Oct/Nov 2023 · Q25 Marks
George has a fair 5-sided spinner with sides labelled 1, 2, 3, 4, 5. He spins the spinner and notes the number on the side on which the spinner lands.
- (a)Find the probability that it takes fewer than 7 spins for George to obtain a 5.[2]
- (b)George spins the spinner 10 times. Find the probability that he obtains a 5 more than 4 times but fewer than 8 times.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.
- [M1] 1-0.8^n, n = 6, 7.
- [A1] 0.738, 11529/15625 (0.737856 to at least 3SF).
- [M1] One term: 10Cx (p)^x (1-p)^(10-x), 0<p<1, x≠0,10.
- [A1] Correct expression, accept unsimplified, no terms omitted leading to final answer.
- [B1] awrt 0.0327
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