A rods manufacturer makes rods with a length that is supposed to be 18

inches. A quality control technician sampled 30

rods and found that the sample mean length was 18.08

inches and the sample standard deviation was 0.23

inches. The technician claims that the mean rod length is less than 18

inches.

What type of hypothesis test should be performed?

What is the test statistic?

What is the number of degrees of freedom?

Does sufficient evidence exist at the =0.1

significance level to support the technician's claim?