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A-LevelMathematicsProbability and statistics9709/53 · Oct/Nov 2022 · Q13 Marks

50 values of the variable x are summarised by Σ(x – 20) = 35 and Σχ² = 25 036. Find the variance of these 50 values.

Mark scheme

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

  1. [B1] Correct value for ∑x or x̄.
  2. [M1] 25036/50 – (their Σx/50)²
  3. [A1] Exact answer only SC B1 for 72.23 with no substitution in formula.

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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 2022 Paper 5 Variant 3, question 1.

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