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2.4.8 Normal distribution as a model (A-level only)

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Question 20

The operating lifetimes of a specific model of industrial drone batteries are normally distributed with mean μ\muμ hours and variance σ2\sigma^2σ2 hours2^22. Based on a single random sample of battery lifetimes, a 99%99\%99% confidence interval for μ\muμ was calculated to be:

(18.22,21.78) (18.22, 21.78) (18.22,21.78)

Using the same sample data,

a.

determine a 95%95\%95% confidence interval for μ\muμ.

[5]
b.

Six independent random samples are taken from the population, and a 95%95\%95% confidence interval is constructed for each sample.

Calculate the probability that exactly 5 of these 6 intervals contain the true population mean μ\muμ.

[3]

2.4.8 Normal distribution as a model (A-level only) Questions

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