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Predicting wins Earlier we investigated the relationship between x =

payroll (in millions of dollars) and y = number of wins for Major League Baseball teams in 2016. Here is a scatterplot of the data, along with the regression line y^=60.7+0.139x

a. Predict the number of wins for a team that spends \(200 million on payroll.

b. Predict the number of wins for a team that spends \)400 million on payroll.

c. How confident are you in each of these predictions? Explain your reasoning.

Short Answer

Expert verified

Part (a) The number of wins is88.5

Part (b) The number of wins is116.3

Part (c) we need to check how confident are we in the results of parts (a) and (b).

Step by step solution

01

Part (a) Step 1: Given information

It is stated in the regression line question that,

yÁåœ=60.7+0.139x

02

Part (a) Step 2: Concept

The most common method for fitting a line to a scatterplot is least squares.

03

Part (a) Step 3: Calculation

As a result, the number of victories for a team with a salary of $200million is computed as follows:

yÁåœ=60.7+0.139x=60.7+0.139(200)=88.5

As a result, for a team with a salary of $200 million, the expected number of victories is 88.5

04

Part (b) Step 1: Calculation

The regression line is provided in the question.

yÁåœ=60.7+0.139x

Thus, the number of wins for a team that spends $400million on payroll is calculated as:

yÁåœ=60.7+0.139x=60.7+0.139(400)=116.3

As a result, for a team with a salary of $400million, the expected number of victories is 116.3

05

Part (c) Step 1: Explanation

The regression line is provided in the question,

yÁåœ=60.7+0.139x

As a result, we must assess our confidence in the results of parts (a) and (b) (b). We can see from the scatterplot that the payroll in the data set appears to range from $75million to 275million dollars.

We are confident in the forecast of the portion since 200million dollars is within the I range of payrolls in the data set (a). We are not confident in the prediction of part (b) since we are using extrapolation and $400million is not within the range of payrolls in the data set.

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