3. A company which produces tennis balls aims to manufacture tennis balls that have a mean internal pressure of 14 psi, with population standard deviation σ = 1.5 psi. In trying

to improve efficiency the company alters their manufacturing process slightly. The company knows that this alteration does not change the standard deviation, however, they are unsure if the mean psi has changed. They sample 9 tennis balls produced after this alteration and find that they have the following psi: 12, 13.5, 11, 16, 15, 10, 14, 14.5, 12. Perform a hypothesis test to check whether the mean psi, μ, has changed by completing the following steps. (a) (2 points) State the null and alternative hypotheses. (b) (4 points) One of the assumptions of hypothesis testing is that the data comes from