Problem 3 (1.5 points)

This question involves using R to perform the multiple linear regression using

the "Carseats" datain from R library of "ISLR".

(a) Fit a multiple regression model to predict "Sales" using "Price", "Urban", and

"US". Use the summary() function to print the results.

(b) Provide an interpretation of each coefficient in the model. It is noted that some

of the input variables in the model are qualitative.

(c) Based on significant level of a = 0.05, for which of the predictors can you

reject the null hypothesis Ho: B; = 0?

(d) On the basis of your response to question (c), fit a smaller model that only uses

the predictors for which there is evidence of association with the outcome.

(e) How well do the models in (a) and (d) fit the data?

(f) Using the model from (d), obtain 99% confidence intervals for the coeffi-

cient(s).

Note: To get full points, include R codes in the appendix sections