Question: A manufacturer claims that the life span of its tires is 50,000 miles. You work for a consumer agency and you are testing these tires. Assume the life spans of the tires are normally distributed. You select 100 tires at random and test them. The mean life span is 49,891 miles Assume o= 700
a) assuming the manufacturer's claim is correct, what is the probability the mean of the sample is 49,891 miles or less?