Page 54 - Probability Demystified
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CHAPTER
The Addition Rules
Introduction
In this chapter, the theory of probability is extended by using what are called
the addition rules. Here one is interested in finding the probability of one
event or another event occurring. In these situations, one must consider
whether or not both events have common outcomes. For example, if you are
asked to find the probability that you will get three oranges or three cherries
on a slot machine, you know that these two events cannot occur at the same
time if the machine has only three windows. In another situation you may be
asked to find the probability of getting an odd number or a number less than
500 on a daily three-digit lottery drawing. Here the events have common
outcomes. For example, the number 451 is an odd number and a number less
than 500. The two addition rules will enable you to solve these kinds of
problems as well as many other probability problems.
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