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12.66 Can the consumption of water in a city be predicted by air temperature? Th

ID: 3224147 • Letter: 1

Question

12.66 Can the consumption of water in a city be predicted by air temperature? The following data represent a sample of a day's water consumption and the high temperature for that day. Temperature Water Use (millions of gallons) degrees Fahrenheit) 103 219 39 56 107 129 50 96 184 90 150 112 Develop a least squares regression line to predict the amount of water used in a day in a city by the high temperature for that day. What would be the predicted water usage for a temperature of 100%? Evaluate the regression model by calculating se, by calculating r and by testing the slope. Let a 01

Explanation / Answer

Solution:

The required regression analysis for the given data for dependent variable water use and independent variable temperature is given as below:

SUMMARY OUTPUT

Regression Statistics

Multiple R

0.954052627

R Square

0.910216416

Adjusted R Square

0.895252485

Standard Error

17.88775727

Observations

8

ANOVA

df

SS

MS

F

Significance F

Regression

1

19463.04384

19463.04384

60.82736097

0.000234226

Residual

6

1919.831161

319.9718602

Total

7

21382.875

Coefficients

Standard Error

t Stat

P-value

Lower 95%

Upper 95%

Intercept

-54.35604265

24.23708914

-2.242680313

0.066103001

-113.6620632

4.949977875

Temperature

2.401066351

0.307860999

7.799189763

0.000234226

1.647757626

3.154375076

The correlation coefficient between the dependent variable water use and independent variable temperature is given as 0.9541, which means there is strong positive linear relationship or association exists between the dependent variable water use and independent variable temperature. The value of the coefficient of determination or the R square is given as 0.9102, which means about 91.02% of the total variation in the dependent variable water use is explained by the independent variable temperature. The standard error Se is given as 17.8878. The p-value for overall regression model is given as 0.000234 which is less than alpha value 0.01, so we reject the null hypothesis that the given regression model is not statistically significant. This means we conclude that the given regression model is statistically significant.

The regression equation is given as below:

Water use = -54.3560 + 2.4011*Temperature

The predicted water use for temperature = 100 is given as below:

Water use = -54.3560 + 2.4011*100

Water use = 185.754

SUMMARY OUTPUT

Regression Statistics

Multiple R

0.954052627

R Square

0.910216416

Adjusted R Square

0.895252485

Standard Error

17.88775727

Observations

8

ANOVA

df

SS

MS

F

Significance F

Regression

1

19463.04384

19463.04384

60.82736097

0.000234226

Residual

6

1919.831161

319.9718602

Total

7

21382.875

Coefficients

Standard Error

t Stat

P-value

Lower 95%

Upper 95%

Intercept

-54.35604265

24.23708914

-2.242680313

0.066103001

-113.6620632

4.949977875

Temperature

2.401066351

0.307860999

7.799189763

0.000234226

1.647757626

3.154375076

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