Suppose that a category of world class runners are known to run a marathon (26 miles) in an average of 145 minutes with a standard deviation of 12 minutes. Consider 49 of the races.

Let
X = the average of the 49 races.

Suppose that a category of world class runners are known to run a marathon 26 miles in an average of 145 minutes with a standard deviation of 12 minutes Conside class=