Answer
a) See below.
b) See below.
Work Step by Step
a) Type 1 error: the probability of rejecting a true null hypothesis.
Type 2 error: the probability of failing to reject a false null hypothesis
b) Type 1: We reject that the sample has a mean of 25, when in fact it does have a mean of 25.
Type 2: We don't reject that the sample has a mean of 25, when in fact it doesn't have a mean of 25.