mg We want to conduct a hypothesis test of the claim that for middle-aged adults the population mean of their cholesterol levels is less than 197.6 . We choose dL a random sample of such levels. The sample has a mean of 192.6 mg mg dL and a standard deviation of 18 TP 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 answers to two decimal places. (a) The sample has size 20, and it is from a normally distributed population with an unknown standard deviation. Oz = Of = O It is unclear which test statistic to use. X 3 ? (b) The sample has size 14, and it is from a normally distributed population with a known standard deviation of 19.3. O z = Ot= O It is unclear which test statistic to use