You would like to construct a 90% confidence interval to estimate the population mean time it takes drivers to react following the application of brakes by the driver in front of them. You take a random sample of reaction time measurements and compute their mean to be 2.4 seconds and their standard deviation to be 0.5 seconds. (a) What is the best point estimate, based on the sample, to use for the population mean? seconds (b) For each of the following sampling scenarios, determine which distribution should be used to calculate the critical value for the 90% confidence interval for the population mean. (In the table, Z refers to a standard normal distribution, and t refers to a t distribution.) Could use Sampling scenario Unclear either Z ort The sample has size 85, and it is from a non-normally distributed population. The sample has size 11, and it is from a normally distributed population with an unknown standard deviation. The sample has size 15, and it is from a normally distributed population with a known standard deviation of 0.45.