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4MA1/1H Jan 2020, Question 4: Estimating the Mean for Grouped Data

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1H (Higher) · Calculator · 7 marks

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The question, in short

Use the grouped frequency table for the weights of 40 babies to find the modal class, estimate the mean weight, and find a probability for a randomly chosen baby.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 1 mark

State which weight interval has the highest frequency.

  1. 1The modal class is the one with the highest frequency.
  2. 2The frequency for 3 < w ≤ 4 is 16, which is higher than all other frequencies.

Answer3 < w ≤ 4

Part (b) · 4 marks

Calculate an estimate of the mean weight of the 40 babies from the grouped table.

  1. 1Midpoints: 2.5, 3.5, 4.5, 5.5, 6.5
  2. 2Frequency × midpoint: 30, 56, 40.5, 11, 6.5
  3. 3Sum = 144
  4. 4Mean = 144 ÷ 40 = 3.6 kg

Answer3.6

Part (c) · 2 marks

Find the probability that a randomly chosen baby weighs more than 5 kg.

  1. 1Number of babies with weight > 5 kg: those in 5 < w ≤ 6 and 6 < w ≤ 7
  2. 22 + 1 = 3
  3. 3Probability = 3 ÷ 40 = 3/40

Answer3/40

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