Long jumps Here are the 40-yard-dash times (in seconds) and long-jump distances (in inches) for a small class of 12 students:

a. Sketch a scatterplot of the data using dash time as the explanatory variable.

b. Use technology to calculate the equation of the least-squares regression line for predicting the long-jump distance based on the dash time. Add the line to the scatterplot from part (a).

c. Explain why the line calculated in part (b) is called the “least-squares” regression line.

Short Answer

Expert verified

Part (b) y=414.786245.7433x

Part (c) A residual is a difference between the actual y-values and the predicted y-values.

Part (a)

Step by step solution

01

Part (a) Step 1: Given information

02

Part (a) Step 2: Concept

The least-squares regression line reduces the sum of squares of vertical distances between the observed points and the line to zero.

03

Part (a) Step 3: Explanation

In the question for the students, the data for the sprint time and the long-jump distance is provided. As a result, the scatterplot for the same is as follows:

On the horizontal axis is the dash time in seconds, while on the vertical axis is the long jump distance in inches.

04

Part (b) Step 1: Calculation

In the question for the students, the data for the sprint time and the long-jump distance is provided. We must now determine the least-squares regression line's equation. As a result,

Linreg(a+bx)L1,L2

Select 1: Edit after pressing STAT for the first time. Then, in list L1enter the data, and in list L2enter the rest of the information. Next, press STATthen pick CALC, then LinReg(a+bx)After that, we must complete the command by entering the list.

Finally pressing on ENTER ten gives us the following results:

y=a+bxa=414.7862b=45.7433r2=0.7023r=0.8380

Thus the equation of the least square regression line will be as:

y=414.786245.7433x

And the line added to the scatterplot in part (a) will be as:

05

Part (c) Step 1: Explanation

In the question for the students, the data for the sprint time and the long-jump distance is provided. Because it is the straight line that minimizes the sum of the squared residuals, the regression line from component (b) is termed the least-squares regression line. The disparity between the actual and expected y-values is known as a residual.

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