3.

a. P(<Xbar) when mu = 50, Xbar = 48, n = 16, sigma = 4

b. P(> Xbar) when mu = 70, Xbar = 70.5, n = 4, sigma = 4

c. P(95</= Xbar </= 105 when mu 100, n = 9, sigma = 6

d. Probability of X < 73 OR probability of X> 79 when mu = 75, n = 36, sigma = 9