A man has designed a machine to produce a compound
and has calibrated it so the compound always has an atomic weight of 20.4. Unbeknownst
to him, the machine has a defect in that it doesn't always produce the compound
with precisely that weight. Assume that the distribution of the weights of the
compounds produced by the machine is normal with a mean of 21.37 and standard
deviation of 0.4

Find the probability that the atomic weight of a single compound chosen at random is less than 22.07