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A-LevelMathematicsProbability and statistics9709/63 · May/June 2022 · Q13 Marks

The number of characters in emails sent by a particular company is modelled by the distribution N(1250, 480²).

  1. (a)Find the probability that the mean number of characters in a random sample of 100 emails sent by the company is more than 1300.[3]

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

  1. [M1] (1300-1250) / (480/10) [= 1.042]
  2. [M1] 1 – Φ('1.042')
  3. [A1] 0.149 (3 s.f.)

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About this question

Topic
Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 3 marks.
Source
A-Level Mathematics, May/June 2022 Paper 6 Variant 3, question 1.

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