A tire manufacturer claims that the lifetime of its tires

Last updated: 12/11/2023

A tire manufacturer claims that the lifetime of its tires are normally distributed with a mean of m 34 000 miles and a standard deviation of a 1200 miles A trucking firm using these tires suspects that the mean lifetime is less than 34 000 miles To test the claim the firm randomly selects and tests 54 of these tires and gets a mean lifetime of 33 390 mi Use a significance level of a 0 05 to test the trucking firm s claim