Andrea conducted an experiment comparing number of helping behaviors of individividuals who just passed a test to those individuals who just failed a test. Using a sample of 27 participants per group, she found that the mean number of times for those who just passed was 19 whereas for those who failed it was 1. Andrea estimated the population standard deviation to be 6. (Use a = .05, two-tailed) 1. What is the effect of this study?
0.25
0.33
0.83
0.50

2. What is the power of this study?

3. Using an effect size of 0.60 ( and a=.05) how many total participants would Andrea need to obtain a power of .94?