Suppose that a category of world class runners are known to run a marathon (26 miles) in an average of 142 minutes with a standard deviation of 14 minutes. Consider 49 of the races. Let X = the average of the 49 races.
1) Find the probability that the runner will average between 139 and 143 minutes in these 49 marathons. (Round your answer to four decimal places.)
2) Find the 80th percentile for the average of these 49 marathons. (Round your answer to two decimal places.)