Final answer:
For a hypothesis test involving a sample of n = 23 from a normally distributed population with known population standard deviation σ = 30, the correct distribution to use is the normal distribution (option a).
Step-by-step explanation:
To determine whether the hypothesis test involves a sampling distribution of means that is a normal distribution, a Student's t-distribution, or neither, we need to consider the sample size and whether the population standard deviation is known. Since the sample data include n = 23, Överbar(x) = 912, and s = 30, and it is mentioned that the sample data appear to come from a normally distributed population with σ = 30, the correct distribution to use would be the normal distribution.
We use the Student's t-distribution when the population standard deviation is unknown and we have to estimate it using the sample standard deviation. However, in this case, since the population standard deviation σ is known and given as 30, we do not need to estimate it and can directly apply the normal distribution for our hypothesis test. Additionally, given that the sample size is less than 30, but the population is normally distributed, the normal distribution is still appropriate.
Therefore, the correct choice is (a) Normal distribution.