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Less mess? Kerry and Danielle wanted to investigate whether tapping on a can of soda would reduce the amount of soda expelled after the can had been shaken. For their experiment, they vigorously shook 40 cans of soda and randomly assigned each can to be tapped for 0 seconds, 4 seconds, 8 seconds, or 12 seconds. After waiting for the fizzing to stop, they measured the amount expelled (in milliliters) by subtracting the amount remaining from the original amount in the can.30 Here is some computer output from a

regression of y = amount expelled on x = tapping time:

a. Is a line an appropriate model to use for these data? Explain how you know.

b. Find the correlation.

c. What is the equation of the least-squares regression line? Define any variables that you use.

d. Interpret the values of s and r2.

Short Answer

Expert verified

Part (a) Yes, a line appears to be appropriate for these data.

Part (b) r=−0.9240

Part (c)yÁåœ=106.360−2.635x

Part (d) The least square regression line utilizing the tapping duration as an explanatory variable can explain 85.38 percent of the variation in the amount ejected.

Step by step solution

01

Part (a) Step 1: Given information

02

Part (a) Step 2: Explanation

In the question, the relationship between the amount expelled and the tapping time in seconds is stated. For the same, a scatterplot and a residual plot are provided. Because there is no substantial curvature in the scatterplot and no strong curvature in the residual plot, it appears that a line is appropriate for these data.

03

Part (b) Step 1: Calculation

In the question, the relationship between the amount expelled and the tapping time in seconds is stated. For the same, a scatterplot and a residual plot are provided. As a result, the coefficient of determination appears after "R-Sq" in the computer output as:

r2=85.38%=0.8538

The positive or negative square root of the coefficient of determination r2yields the linear correlation coefficient rAs a result, we can see that the scatterplot pattern slopes downwards, indicating a negative relationship between the variables and, as a result, a negative linear correlation coefficient rThis indicates that,

r=−r2=−0.8538=−0.9240

04

Part (c) Step 1: Calculation

In the question, the relationship between the amount expelled and the tapping time in seconds is stated. For the same, a scatterplot and a residual plot are provided. The least square regression line's general equation is:

yÁåœ=b0+b1x

As a result, the estimate of the constant b0is given in the computer output's row "Constant" and column "Coef" as:

b0=106.360

In the computer output, the estimate of the slope b1is presented in the row "Tapping time" and the column "Coef" as:

b1=−2.635

As a result, when we plug the values into the general equation, we get:

yÁåœ=b0+b1x⇒yÁåœ=106.360−2.635x

05

Part (d) Step 1: Calculation

In the question, the relationship between the amount expelled and the tapping time in seconds is stated. For the same, a scatterplot and a residual plot are provided. As a result, after "S=" in the computer output, the standard error of the estimations is given as:

s=5.00347

The standard error of the estimations, as we all know, is the average error of forecasts, and thus the average difference between actual and predicted values. As a result, the predicted amount evacuated using the least square regression line differed by 5.00347ml on average from the actual amount expelled.

In the computer output, the coefficient of determination is now given after "R-Sq" as:

r2=85.38%=0.8538

The coefficient of determination, as we know, is a measurement of how much variation in the answers y variable is explained by the least square regression model with the explanatory variable. As a result, the least square regression line utilizing the tapping duration as an explanatory variable can explain 85.38the percent of the variation in the amount ejected.

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Most popular questions from this chapter

One child in the Mumbai study had height 59 cm and arm span 60 cm. This child’s residual is

a. −3.2 cm.

b. −2.2 cm.

c. −1.3 cm.

d. 3.2 cm.

e. 62.2 cm.

Sarah’s parents are concerned that she seems short for her age. Their doctor has kept the following record of Sarah’s height:

a. Make a scatterplot of these data using age as the explanatory variable. Describe what you see.

b. Using your calculator, find the equation of the least-squares regression line.

c. Calculate and interpret the residual for the point when Sarah was 48 months old.

d. Would you be confident using the equation from part (b) to predict Sarah’s height when she is 40 years old? Explain.

Late bloomers? Japanese cherry trees tend to blossom early when spring weather is warm and later when spring weather is cool. Here are some data on the average March temperature (in degrees Celsius) and the day in April when the first cherry blossom appeared over a 24-year period:

a. Make a well-labeled scatterplot that’s suitable for predicting when the cherry trees will blossom from the temperature. Which variable did you choose as the explanatory variable? Explain your reasoning.

b. Use technology to calculate the correlation and the equation of the least-squares regression line. Interpret the slope and y-intercept of the line in this setting.

c. Suppose that the average March temperature this year was 8.2°C. Would you be willing to use the equation in part (b) to predict the date of the first blossom? Explain your reasoning.

d. Calculate and interpret the residual for the year when the average March temperature was 4.5°C.

e. Use technology to help construct a residual plot. Describe what you see.

Using data from the LPGA tour, a regression analysis was performed using x = average driving distance and y = scoring average. Using the output from the regression analysis shown below, determine the equation of the least-squares regression line.

a. y^=87.974+2.391x

b. y^=87.974+1.01216x

c. y^=87.974−0.060934x

d. y^=−0.060934+1.01216x

e. y^=−0.060934+87.947x

More wins? Refer to Exercise 37

a. Interpret the slope of the regression line.

b. Does the value of the y-intercept have meaning in this context? If so, interpret the y-intercept. If not, explain why.

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