Test Whether He Given Claim Is Supported or Not Supported

Test whether he given claim is supported or not supported using a 0.05 significance level. Assume that the sample has been randomly selected from a population with a normal distribution.
-A trucking firm suspects that the mean life of a certain tire it uses is less than 34,000 miles. To check the claim, the firm randomly selects and tests 18 of these tires and gets a mean lifetime of 33,400 miles with a standard deviation of 1200 miles. Use a 0.05 significance level to test whether the trucking firm's claim is supported or not supported.

A) supported
B) not supported