In the past, a company found that the mean number of overtime hours for its employees was 10.5 hours per month. However, a recent sample of 40 employees showed that the mean number of overtime hours in a month was 12.3, with s = 4.4 hours. Test the claim, at a significance level of 0.01, that the mean number of overtime hours per month exceeds 10.5 for all employees of this company:
a) Write the null and alternative hypotheses:

b) Find the value of the test statistic (rounded properly):

c) Find the critical value, and sketch the rejection region

d) We will reject / fail to reject H0.

e) Make a statement with your conclusion in the context of the problem