Suppose I want to estimate the "mean household income" of a neighborhood within a city. I get a sample of 60 households and ask them of their household income. The mean household income for this sample of 60 households in US dollars was 56,000. The population standard deviation can be assumed to be 15,000. The distribution to be used for interval estimate on mean household income is:
a) I don't need to do an interval estimate, I know the mean already
b) Z
c) Exponential
d) none of the other answers listed here are correct
e) Binomial
f) It cannot be estimated
g) Poisson
h) t