You would like to construct a 90% confidence interval to estimate today's population mean temperature, so you make a series of measurements (a random sample) throughout the day. The mean of these measurements is 58 degrees Fahrenheit, and their standard deviation is 3 degrees Fahrenheit. (a) What is the best point estimate, based on the sample, to use for the population mean? X ? degrees (b) For each of the following sampling scenarios, determine which distribution should be used to calculate the criticals value for the 90% confidence interval for the population mean. (In the table, Z refers to a standard normal distribution, and { refers to a t distribution.) Could use Sampling scenario Z 1 Unclear either Z or t The sample has size 105, and it is from a non-normally distributed X 3 ? O O O O population with a known standard deviation of 3. The sample has size 110, and it is from a non-normally distributed O population. The sample has size 16, and it is from a normally distributed O O O O population with an unknown standard deviation