In 58 specimens of a new aluminum alloy that is developed as a material for the next generation of aircraft, the compressive strength was measured, obtaining the following results: XXXXXXXXXX...

In 58 specimens of a new aluminum alloy that is developed as a material for the next generation of aircraft, the compressive strength was measured, obtaining the following results:

66.4 67.7 68.0 68.0 69.5 70.4 71.6 72.9 69.0 69.1
69.2 69.3 69.3 69.5 70.3 71.5 72.7 68.9 69.9 70.0
70.0 70.1 70.2 70.3 71.3 72.6 68.8 69.8 70.8 70.9
71.0 71.1 71.2 71.3 72.4 68.6 69.8 70.6 71.8 71.8
71.9 72.1 72.2 72.3 68.4 69.7 70.6 71.7 73.3 73.5
74.2 74.5 75.3 68.3 69.6 70.5 71.6 73.1

a. Find a 95% confidence interval for the mean resistance of the
aluminium alloy.
b. If you want to test Ho:Mu =72 against H1: Mu different from 72 with a significance level of 0.05, what is the probability of a type II error for Mu=  71?