The number of customers who visit a particular shop between 9.00 am and 10.00 am has the distribution Po(λ). In the past the value of λ was 5.2. Following some new advertising, the manager wishes to test whether the value of λ has increased. He chooses a random sample of 20 days and finds that the total number of customers who visited the shop between 9.00 am and 10.00 am on those days is 125. Use an approximating distribution to test at the 2.5% significance level whether the value of λ has increased.

1. Use an approximating distribution to test at the 2.5% significance level whether the value of λ has increased.[6]