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A-LevelMathematicsProbability and statistics9709/61 · Oct/Nov 2023 · Q13 Marks

A random variable X has the distribution N(410, 400). Find the probability that the mean of a random sample of 36 values of X is less than 405.

(a)Find the probability that the mean of a random sample of 36 values of X is less than 405.[3]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.

[M1] For standardising, must have √36. Allow totals method 14580-14760/√14400 No mixed methods.
[M1] For area consistent with their working.
[A1]

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About this question

Topic: Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 3 marks.
Source: A-Level Mathematics, Oct/Nov 2023 Paper 6 Variant 1, question 1.

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