The weights of a random sample of 12 luxury chocolates are measured. The mean weight of the sample is recorded as 42.5 g42.5\text{ g}42.5 g. The weights of the chocolates are known to be normally distributed.
Given that the population standard deviation is 0.8 g0.8\text{ g}0.8 g,
estimate the limits between which 95%95\%95% of the weights of individual chocolates lie.
find a 99%99\%99% confidence interval for the mean weight of the chocolates.
A quality control manager claims that the mean weight of these chocolates is 41.8 g41.8\text{ g}41.8 g.
Comment on the manager's claim. Give a reason for your answer.
616 exam-style questions on Edexcel A Level Maths The Normal Distribution, covering 3.1 The Normal Distribution, 3.2 Finding Probabilities for Normal Distributions, 3.3 The Inverse Normal Distribution Function, 3.4 The Standard Normal Distribution, 3.5 Finding the mean and standard deviation, 3.6 Approximating a Binomial Distribution, and 3.7 Hypothesis Testing with the Normal Distribution. Each one has a worked solution and a mark scheme showing where the marks go.