Edexcel S3 2021 October — Question 5

Exam BoardEdexcel
ModuleS3 (Statistics 3)
Year2021
SessionOctober
TopicHypothesis test of a normal distribution

  1. Assam produces bags of flour. The stated weight printed on the bags of flour is 3 kg . The weights of the bags of flour are normally distributed with standard deviation 0.015 kg .
Assam weighs a random sample of 9 bags of flour and finds their mean weight is 2.977 kg .
  1. Calculate the \(99 \%\) confidence interval for the mean weight of a bag of flour. Give your limits to 3 decimal places. Assam decides to increase the amount of flour put into the bags.
  2. Explain why the confidence interval has led Assam to take this action. After the increase a random sample of \(n\) bags of flour is taken. The sample mean weight of these \(n\) bags is 2.995 kg . A \(95 \%\) confidence interval for \(\mu\) gave a lower limit of less than 2.991 kg .
  3. Find the maximum value of \(n\).
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