5 The number of customers arriving at a store between 8.50 am and 9 am on Saturday mornings is a random variable which can be modelled by the distribution \(\operatorname { Po } ( 11.0 )\). Following a series of price cuts, on one particular Saturday morning 19 customers arrive between 8.50 am and 9 am . The store's management claims, first, that the mean number of customers has increased, and second, that this is due to the price cuts.
- Test the first part of the claim, at the \(5 \%\) significance level.
- Comment on the second part of the claim.