A manufacturer of strapping tape claims that the tape has a mean breaking strength of 500 psi. Experience has shown that breaking strengths are approximately normally distributed, with a standard deviation of 48 psi. A random sample of 16 specimens is drawn from a large shipment of tape, and a mean of 480 psi is computed. Can we conclude from these data that the mean breaking strength for this shipment is less than that claimed by the manufacturer? Let alpha = 0.05.
a. Will you use z or t?
b. Find the critical value and the test statistic.
c. Find the p-value. What is your conclusion?