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...

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: μ = 4.0 versus H₁: μ ≠ 4.0. a) Make a dotplot of the seven values. b) Should a Student's t test be used to test H₀? If so, perform the test. If not, explain why not. c) Measurements are taken of the wall thicknesses of seven bottles of a different type. The measurements this time are: 4.004, 4.225, 3.924, 4.052, 3.975, 3.976, and 4.041. Make a dotplot of these values. d) Should a Student's t test be used to test H₀: μ = 4.0 versus H₁: μ ≠ 4.0? If so, perform the test. If not, explain why not.