Question

Let X model the racing times for local high school athletes in the 400 meter dash. Assume that X is normally distrubuted with a mean of 60 seconds, and a standard deviation of 4.7 secinds. Assuming your friens can run 400 meters in 63 secinds. What is the probability that a local high school athlete is faster by at least one second? What is the probabilty that the mean race time for a group of 8 track athletes exceeds 61 seconds?

Answer 1

faster by at least one second means he completed with less than or equal to 62 seconds.