An experiment was conducted to test the effects of alcohol. The errors were recorded in a test of visual and motor skills for a treatment group of people who drank ethanol and another group given a placebo. The results are shown in the accompanying table. Use a 0.05 significance level to test the claim that the two groups come from populations with the same mean. Do these results support the common belief that drinking is hazardous for drivers, pilots, ship captains, and so on?

Based on data from "Effects of Alcohol Intoxication on Risk Taking, Strategy, and Error Rate in Visuomotor Performance," by Streufert et al., Journal of Applied Psychology, Vol. 77, No. 4.

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Treatment Group nl = 22 x, = 4.20 s, = 2.20 Placebo Group x, = 1.71 s2 = 0.72