AQA S1 2014 June — Question 7

Exam BoardAQA
ModuleS1 (Statistics 1)
Year2014
SessionJune
TopicCentral limit theorem
TypeDistribution of sample mean

7 The volume of water, \(V\), used by a guest in an en suite shower room at a small guest house may be modelled by a random variable with mean \(\mu\) litres and standard deviation 65 litres. A random sample of 80 guests using this shower room showed a mean usage of 118 litres of water.
    1. Give a numerical justification as to why \(V\) is unlikely to be normally distributed.
    2. Explain why \(\bar { V }\), the mean of a random sample of 80 observations of \(V\), may be assumed to be approximately normally distributed.
    1. Construct a \(98 \%\) confidence interval for \(\mu\).
    2. Hence comment on a claim that \(\mu\) is 140 .
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