Given mean = 167cm, standard deviation is 3cm,
a) When four are randomly selected, all of their heights will be greater than 170?
b) When four are randomly selected, two will have heights smaller than the mean, two will have heights greater than the mean?
For a) it is just [P(Z > 1)]^4 = 0.00063
For b) it is (0.5)^2 + (0.5)^2
Is my methodology correct?