When testing for a difference between the means of a treatment group and a group given a placebo, the following Excel display is obtained. Using a 0.02 significance level, is there sufficient evidence to support the claim that the treatment group (Variable 1) comes from a population with a mean that is different from the mean for the placebo population? Explain.

Transcribed Image Text:

1 z-Test: Two Sample for Means 2 Variable Variable 2 4 Mean 5 Known variance 6 Obsevations 7 Hypothesized mean difference 75.34798 73.81763 1.55383 11.65292 50 50 P(Z<=z) one-tail z Critical one-tail P(Z<=z) two-tail z Critical two-tail 2.199422 0.013924 1.644853 0.027848 1.959961 9 10 11 12