The thickness of plastic film (in mils) on a substrate material is thought to be influenced by the temperature at which the coating is applied. A completely randomized experiment is carried out. Eleven substrates are coated at 125 degree F, resulting in a sample mean coating thickness of = 103.5 and a sample standard deviation of S1 = 10.2. another 13 substrates are coated at 150 degree F, for which = 99.7 and s2 = 20.1 are observed. It was originally suspected that raising the process temperature would reduce mean coating thickness. Do the data support this claim? Use alpha = 0.01 and assume that the two population standard deviations are not equal. Calculate an approximate P - value for this test. How could you have answered the question posed regarding the effect of temperature on coating thickness by using a confidence interval? Explain your answer.