We want to conduct a hypothess test of the clam that for middle-aged adults the population mean of their cholesterol leves is more than 193.3 We mg choose a tandam.sample of such levels. The sample has a mean of 192.3 mg and a tandard deviation of 18 dL For each of the following samplang scenarios, choose an appropriate tet statistic for our hypothesis test on the pepulaton mean. Then calculate that statist. Round your answers to twn decimal places (a) The samole has sze 13, and it is from a normaly dstributed population with an unknown standard deviatikon. ORunclear which test statistic to use (b) The sample has se 12 and it is from a normaly datributed poputation with a known atandard deviation of 19.2 or-0 ORsundear which test statistic to use