Probability theory is probably the least understood area by the general population (except for certain gamblers). As a simple example, consider the History Professor friend of mine who was scared of flying and asked me one day: ""What is the probability that there will be a bomb on an airplane?"" I responded that I really didn't know, but that it was certainly less than one in a million. So he asked: ""Well, what is the probability that there are two bombs on an airplane?"" I responded that (as long as these were independent events) it would be the square of the probability of having one bomb, which is 1 in a trillion - a truly astronomical number. So, from that day forward he always carried a bomb with him when he flew since it reduced the risk of having a bomb on the plane from 1 in a million to 1 in a trillion.