Bluman A.G. Elementary Statistics- A Step By Step Approach

Section 5–1 Probability Distributions 255Figure 5–1Probability Distributionfor Example 5–2Probability382818P(X)X0 12 3Number of headsExample 5–3Baseball World SeriesThe baseball World Series is played by the winner of the National League and theAmerican League. The first team to win four games wins the World Series. In otherwords, the series will consist of four to seven games, depending on the individualvictories. The data shown consist of 40 World Series events. The number of gamesplayed in each series is represented by the variable X. Find the probability P(X) foreach X, construct a probability distribution, and draw a graph for the data.X Number of games playedSolution4 85 76 97 1640The probability P(X) can be computed for each X by dividing the number of games Xby the total.For 4 games,8940 0.200 For 6 games, 40 0.225For 5 games,71640 0.175 For 7 games, 40 0.400The probability distribution isNumber of games X 4 5 6 7Probability P(X) 0.200 0.175 0.225 0.400The graph is shown in Figure 5–2.Figure 5–2P(X)Probability Distributionfor Example 5–30.40Probability0.300.200.10045Number of games6 7X5–5