For each of the following scenarios, indicate which test statistic would be used or which test could not be conducted using the materials from this chapter:
a. testing a mean when s is known and the population sampled from has a normal distribution
b. testing a mean when s is unknown and the population sampled from has a normal distribution
c. testing a proportion in which np = 12 and n (1 – p) = 4
d. Testing a mean when s is obtained from a small sample and the population sampled from has a skewed distribution