In a test of the effects of marijuana use on mental abilities, the following were discovered:
Items sorted correctly by light marijuana users: x-var= 53.5, s=3.6, n=64
Items sorted corectly by heavy marijuana uses: x-var= 51.3, s=4.5, n=65
Does the population of heavy marijuana users have a lower mean than the light users?
Use signify(range error)=.01