EXAMPLE 3 Classical method: Single draw from a deck of cards

Find the probability of drawing an ace when drawing a single card at random from a deck of cards.

Solution

The sample space for the experiment in which a subject chooses a single card at random from a deck of cards is given in Figure 1. If the card is chosen truly at random, then it is reasonable to assume that each card has the same chance of being drawn. Each card is equally likely to be drawn, so we can use the classical method to assign probabilities.

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Figure 5.1: FIGURE 1 Sample space for drawing a card at random from a deck of cards.

A total of 52 outcomes are included in this sample space, so . Let be the event that an ace is drawn. Event consists of the four aces {A ♥, A♦, A♣, A♠}, so . Therefore, the probability of drawing an ace is

NOW YOU CAN DO

Exercises 21–24.