A-LevelMathematicsProbability and statistics9709/63 · May/June 2017 · Q14 Marks

A biased die has faces numbered 1 to 6. The probabilities of the die landing on 1, 3 or 5 are each equal to 0.1. The probabilities of the die landing on 2 or 4 are each equal to 0.2. The die is thrown twice. Find the probability that the sum of the numbers it lands on is 9.

A biased die has faces numbered 1 to 6. The probabilities of the die landing on 1, 3 or 5 are each equal to 0.1. The probabilities of the die landing on 2 or 4 are each equal to 0.2. The die is thrown twice. Find the probability that the sum of the numbers it lands on is 9.[4]

Mark scheme

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

[B1] P(6) = 0.3 SOI
[M1] Identifying the four ways of summing to 9 (3,6), (6,3) (4,5) and (5,4)
[M1] Mult 2 probs together to find one correct prob of (3,6), (6,3) (4,5) or (5,4) unsimplified
[A1] = 0.1 OF

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Topic: Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 4 marks.
Source: A-Level Mathematics, May/June 2017 Paper 6 Variant 3, question 1.

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