We want to conduct a hypothesis test of the claim that the middle aged adults population mean of their cholesterol level is more than 198.4 mg/dL. We cose a random sample of such levels. The sample has a mean of 195.4mg/dL and a standard deviation of 19 mg/dL.

For each of the following sampling scenarios, choose an appropriate test statistic for our hypothesis test on the population mean. Then calculate that statistic.

Round your answer to 2 decimal places

a). The sample has size 18, and it is from a population with a distribution about which we know very little.

z=

t=

It is unclear which test statistic to use.

b).The sample has size 13, and it is from a normally distributed population with a known standard deviation of 19.1.

z=

t=

It is unclear which test statistic to use