The Los Angeles County Metropolitan Transportation Authority has set a bus mechanical reliability goal of 3,900 bus miles. Bus mechanical reliability is measured specifically as the number of bus miles between mechanical road calls. Suppose a sample of 100 buses resulted in a sample mean of 3,975 bus miles and a sample standard deviation of 275 bus miles.

a. Is there evidence that the population mean bus miles is greater than 3,900 bus miles? (Use a 0.05 level of significance.)

b. Determine the p-value and interpret its meaning.