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4.2.2 Statistical distributions (A-level only)

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Question 22

An electronics engineer measures the resistance, rrr ohms, of a specific component. The measured resistance, XXX ohms, is normally distributed with mean rrr ohms and standard deviation 0.80.80.8 ohms.

a.

Find the probability that XXX is within 1.01.01.0 ohm of rrr.

[2]
b.

The same component is measured 25 times and the results are recorded.

Find the probability that the sample mean of these 25 results, Xˉ\bar{X}Xˉ, is within 0.40.40.4 ohms of rrr.

[3]
c.

Given that the mean of these 25 measurements is 120.4120.4120.4 ohms, find a 95%95\%95% confidence interval for rrr.

[3]
Markscheme

4.2.2 Statistical distributions (A-level only) Questions

  1. A Level
  2. /Maths
  3. /4.2.2 Statistical distributions (A-level only)

292 exam-style questions on WJEC A Level Maths 4.2.2 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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