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Ever-cool brand of refrigerators | Complete Solution
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 Price(\$) Promotional exp(K) Qualityof Service City:1/Suburban:0 Monthly Sales(K) 904 5 9.5 1 168 909 4.3 4.5 0 168 915 3 8.5 1 162 921 2 5.5 0 160 934 0.75 6.5 1 154 941 4.8 10 0 152 949 3.6 4.25 1 150 953 3 5.5 1 146 955 1.5 7.5 0 146 962 0.7 9.5 0 144 978 4.7 9 1 134 990 3.5 7 0 130 1006 2.8 5 1 122 1014 1.3 4 0 118 1018 0.25 9 1 116 1021 4.5 6 1 114 1022 3.2 5 0 114 1038 2.4 8 0 106 1040 1.2 4 1 104 1050 0 9 0 100

Please consider the data presented above for the monthly sales of Ever-cool brand of refrigerators in 1,000s of dollars and answer the following questions:

Independent variables are as follows.

Price(in dollars); Promotional Expenditure (in 1,000s of dollars); Quality of service ( scale of 1-10); location (categorical variable: city area : 1; suburban area : 0) .

a. Based on  4 in 1 plot and the plots of independent variables vs. residuals, do you see any evidence of violation of assumptions?

b. State the multiple regression equation and interpret the meaning of the slopes, b1, b2, b3, and b4.

c. At the 0.05 level of significance, determine whether each independent variable makes a significant contribution to the regression model. On the basis of these results, indicate the independent variables to include in this model. (Based on t - test results)

d. Construct a 95% confidence interval estimate of the population slope between price and the monthly sales ()

e. Perform the overall F- test and comment on the significance of the model.

• Use MINITAB to run the analysis.