We want to conduct a hypothesis test of the claim that for middle aged adults the population mean of their cholesterol levels is more than 198.4mg/dL. We choose a random sample of such levels. The sample mean of 196.4 mg/dL and a standard deviation of 19 mg/dL.

a). The sample has a size of 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