8.- Many studies have been conducted to test the effects of marijuana use on mental abilities. In one such study, groups of light and heavy users of marijuana in college were tested for memory recall, with the summary results given below. Marijuana Light Use n Mean Standard Deviation n = 65 = 53.3 1 s = 3.6 Heavy Use n = 65 = 51.3 1 S = 4.5 a) Use a 0.01 significance level to test the claim that the population of heavy marijuana users has a lower mean than the light users. Fill in the expressions below Answer: H: H: = Critical Value = Rejection Region = P-value= Conclusion: Keep H 0 Test statistics - Reject H 0 b) Which confidence level is appropriate here to construct a confidence interval for the difference between the two population means.