Question

Tensile strength tests were performed on two different grades of aluminum used in manufacturing the wing of commercial transport aircraft. The following table gives summary statistics for 12 tests on each of two grades.

Summary statistic	Grade I	Grade II	Difference
Average	88.6	75.5	13.1
Standard Deviation	2.0	3.5	2.75

Suppose we test if the tensile strength is higher for the first grade than the second grade, finding 1.164 as the standard error of the appropriate estimate. What are the respective test statistic and degrees of freedom?

Answer 1

we will perform t-test