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4024/11 Oct/Nov 2021, Question 16: Averages from Frequency Tables

Cambridge O Level Mathematics 4024 · Paper 11 (Non-calculator) · Non-calculator · 4 marks

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The question, in short

A spinner with faces 1 to 4 is spun repeatedly and results are tabulated with frequencies 6, 5, 13 and p. Given the mean is 3, work out p, then use p = 17 to get a relative frequency.

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Part (a) · 3 marks

Using the mean of 3 and the frequencies 6, 5, 13 and p, determine the unknown frequency p.

  1. 1(1 × 6 + 2 × 5 + 3 × 13 + 4p)/(6 + 5 + 13 + p) = 3
  2. 255 + 4p = 3(24 + p) = 72 + 3p
  3. 3p = 17

Answer17

Part (b) · 1 mark

Taking p as 17, work out the relative frequency for the outcome 2.

  1. 1Total spins = 24 + 17 = 41
  2. 2Relative frequency of 2 = 5/41

Answer5/41

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