Question

A manufacturing company produces valves in various sizes and shapes. One particular valve plate is supposed to have a tensile strength of 5 pounds per millimeter (lbs/mm). The company tests a random sample of 41 such valve plates from a lot of 640 valve plates. The sample mean is a tensile strength of 5.0588 lbs/mm, and the population standard deviation is 0.2803 lbs/mm. Use α = 0.10 and test to determine whether the lot of valve plates has an average tensile strength of 5 lbs/mm.

Answer 1