Probability in the Everyday world
It is generally agreed that the science of probability began in the sixteenth century from the so-called problem of the points. The problem is to determine the division of the stakes of two equally skilled players when a game of chance is interrupted before either player has obtained the required number of points in order to win. However, real progress on this subject began in 1654 when Chevalier de Mere, an experienced gambler whose theoretical understanding of the problem did not match his observations, approached the mathematician Blaise Pascal for assistance.
Pascal communicated with Fermat about the problem and, remarkably, each solved the problem by different means. Thus, in this correspondence, Pascal and Fermat laid the foundations of probability.
Now, probability is recognized in many aspects of our lives. For example, when you were conceived, you could have had any of 8,388,608 different sets of characteristics hased on 23 pairs of chromosomes. In school, if you guess at random on a 10-item true/false test, there is only about a 17% probability that you will answer 7 or more questions correctly. In the manufacturing process, quality control is becoming the buzzword. Thus it is important to know the probability that certain parts will fail when deciding to revamp a production process or offer a warranty. In investments, advisers assign probabilities to future prices in an effort to decide among various investment opportunities. Another important use of probability is in actuarial science, which is used to determine insurance premiums. Probability also continues to play a role in games of chance such as dice and cards.
One very popular application of probability is the famous “birthday problem.” Simply stated, in a group of people, what is the probability of two people having the same month and day of birth? Surprisingly, the probability of such matching birth dates is about 0.5 when there are 23 people and almost 0.9 when there are 40 people. An interesting application of this problem is the birthdays of the 43 American presidents through George W. Bush: Presidents Polk and Harding were both born on November 2.