Specifications call for the wall thickness of two-liter polycarbonate bottles to average 4.0 mils. A quality control engineer samples 7 two-liter polycarbonate bottles from a large batch and measures the wall thickness (in mils) in each. The results are: 3.999, 4.037, 4.116, 4.063, 3.969, 3.955, and 4.091. It is desired to test H₀ : ? = 4.0 versus H₁ : ? ? 4.0.

Should a Student's t test be used to test H₀? If so, perform the test. If not, explain why not. Check all that are true.

V A Student's t test can be used to test Ho because the sample contains no outliers. A Student's ttest cannot be used to test Ho, because the sample contains outliers. It can be concluded that the mean thickness differs from 4 mils because the P-value is small. It cannot be concluded that the mean thickness differs from 4 mils, because the P-value is large