del 5. A phone industry manager thinks that customer monthly cell phone bill have increased, and now average over $52 per month with a standard deviation of $10. The company wishes to test this claim at 10% significance level by choosing a sample size of n= 64 customers where average cell phone bill was x = $53.1. Using the sample results test the manager's claim (i.e., if it averages over $52 dollars per month).