A manufacturer claims that the average tensile strength of

Last updated: 8/10/2022

A manufacturer claims that the average tensile strength of thread A exceeds the average tensile strength of thread B by at least 12 kilograms. To test this claim, 50 pieces of each type of thread were tested under similar conditions. Type A the thread had an average tensile strength of 86.7 kilograms with a standard deviation of 6.28 kilograms, while type B thread had an average tensile strength of 77.8 kilograms with a standard deviation of 5.61 kilograms. Test the manufacturer's claim using a 0.05 level of significance. What is the type of test to be used? A) z-test, two-tailed B) t-test, two tailed C) z-test, right tailed D) z-test, left tailed E t-test left tailed F t-test, right-tailed