ABSTRACT
This chapter considers situations in which selections are made, yet the order of selecting items is not relevant. Examples of such situations include selecting the members of a committee, choosing numbers for a weekly lottery, and dealing cards from a deck of playing cards. We develop a useful principle for counting outcomes in which the order of selection doesn’t matter. The resulting Combinations Formula can then be applied to calculate the probability of complex events. Having such a generally applicable formula is especially useful since our intuition may not be a reliable guide in assessing probabilities in more complicated situations.
