A sports statistician was interested in the relationship between game attendance (in thousands) and the number of wins for baseball teams. Information was collected on several teams and was used to obtain the regression equation [tex]\hat{y} = 4.9x + 15.2[/tex], where [tex]x[/tex] represents the attendance (in thousands) and [tex]\hat{y}[/tex] is the predicted number of wins.

Which statement best describes the meaning of the [tex]y[/tex]-intercept of the regression line?

A. When the number of wins is 0, the predicted attendance is 0.
B. When the number of wins is 0, the predicted attendance is 15,200.
C. When the attendance is 0, the predicted number of wins is 4.9.
D. When the attendance is 0, the predicted number of wins is 15.2.



Answer :

The regression equation provided is [tex]\(\hat{y} = 4.9x + 15.2\)[/tex], where [tex]\(x\)[/tex] represents the game attendance (in thousands) and [tex]\(\hat{y}\)[/tex] is the predicted number of wins.

To understand the meaning of the [tex]\(y\)[/tex]-intercept:
1. The [tex]\(y\)[/tex]-intercept, given mathematically as the constant term in the regression equation, is 15.2.
2. The [tex]\(y\)[/tex]-intercept represents the value of [tex]\(\hat{y}\)[/tex] when [tex]\(x\)[/tex] is 0. That is, it tells us the predicted number of wins when the game attendance [tex]\(x\)[/tex] is 0.

When the attendance ([tex]\(x\)[/tex]) is 0, substituting [tex]\(x = 0\)[/tex] into the regression equation:
[tex]\[ \hat{y} = 4.9(0) + 15.2 = 15.2 \][/tex]

Therefore, when the attendance is 0 (meaning no one attends the game), the predicted number of wins ([tex]\(\hat{y}\)[/tex]) is 15.2.

Thus, the statement that best describes the meaning of the [tex]\(y\)[/tex]-intercept of the regression line is:
"When the attendance is 0, the predicted number of wins is 15.2."