4-19 Bus and subway ridership in Washington, D.C., dur-ing the summer months is believed to be heavily tied to the number of tourists visiting the city. During the past 12 years, the following data have been obtained:

YEAR 1 2 3 4 5 6 7 8 9 10 11 12 NUMBER OF TOURISTS (1,000,000s) 7 2 6 4 14 15 16 12 14 20 15 7 RIDERSHIP (100,000s) 15 10 13 15 25 27 24 20 27 44 34 17

(a) Plot these data and determine whether a linear model is reasonable.

(b) Develop a regression model.

(c) What is expected ridership if 10 million tourists

(d) If there are no tourists at all, explain the pre-dicted ridership.

4-30 In 2012, the total payroll for the New York Yankees was almost $200 million, while the total payroll for the Oakland Athletics (a team known for using baseball analytics or sabermetrics) was about $55 million, less than one-third of the Yankees' payroll. In the following table, you will see the payrolls (in millions) and the total number of victories for the baseball teams in the American League in the 2012 season. Develop a regression model to predict the to-tal number of victories based on the payroll. Use the model to predict the number of victories for a team with a payroll of $79 million. Based on the results of the computer output, discuss the relationship be-tween payroll and victories.

TEAM Baltimore Orioles Boston Red Sox Chicago White Sox Cleveland Indians Detroit Tigers Kansas City Royals Los Angeles Angels Minnesota Twins New York Yankees Oakland Athletics Seattle Mariners Tampa Bay Rays Texas Rangers Toronto Blue Jays PAYROLL ($1,000,000s) 81.4 173.2 96.9 78.4 132.3 60.9 154.5 94.1 198.0 55.4 82.0 64.2 120.5 75.5 NUMBER OF VICTORIES 93 69 85 68 88 72 89 66 95 94 75 90 93 73

4-32 The closing stock price for each of two stocks was recorded over a 12-month period. The closing price for the Dow Jones Industrial Average (DJIA) was also recorded over this same time period. These val-ues are shown in the following table:

MONTH DJIA 11,168 1 2 3 4 5 6 7 8 9 10 11 12 13 11,150 11,186 11,381 11,679 12,081 12,222 12,463 12,622 12,269 12,354 13,063 13,326 STOCK 1 STOCK 2 48.5 48.2 44.5 44.7 49.3 49.3 46.1 46.2 47.7 48.3 47.0 47.9 47.8 32.4 31.7 31.9 36.6 36.7 38.7 39.5 41.2 43.3 39.4 40.1 42.1 45.2