A company manufactures a large number of rods. The lengths of the rods are normally distributed with a mean length of 4.0 inches and a standard deviation of .75 inches. If you choose a rod at random, what is the probability that the rod you choose will be:
a) Less than 3.0 inches?
b) Greater than 3.7 inches?
c) Between 3.5 and 4.3 inches?