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.
- Give a numerical justification as to why \(V\) is unlikely to be normally distributed.
- Explain why \(\bar { V }\), the mean of a random sample of 80 observations of \(V\), may be assumed to be approximately normally distributed.
- Construct a \(98 \%\) confidence interval for \(\mu\).
- Hence comment on a claim that \(\mu\) is 140 .
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