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 results given below.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.

Items sorted correctly by light marijuana users: n =64, x-(X bar) = 53.3, s = 3.6

Items sorted correctly by heavy marijuana users: n = 65, x-(X bar) = 51.3, s = 4.5