As in Exercise 3, cholesterol levels in healthy U.S. adults average about 215 mg/dL with a standard

Question:

As in Exercise 3, cholesterol levels in healthy U.S. adults average about 215 mg/dL with a standard deviation of about 30 mg/dL and are roughly Normally distributed. If the cholesterol levels of a sample of 42 healthy US adults is taken, what is the probability that the mean cholesterol level of the sample
a) Will be no more than 215?
b) Will be between 205 and 225?
c) Will be less than 200?
d) Will be greater than 220?