A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of this trial, they wish to determine whether there is a difference between the effectiveness for women and for men. At = .05, what is the value the test statistic?
Women Men
Sample size 50 80
Mean effect 7 6.95
Sample variance 3 4
A. t = 3.252
B. z = 0.455
C. z = 0.081
D. z = 0.151