The following model was fitted to describe the selling prices of condominiums in a sample of 815 sales:
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Y = -1264 +48.18x1 + 3382x2 - 1859x3 + 3219x4 +2005x5 ____
(0.91) (515) (488) (947) (768) (768) R^2 = 0.86
where
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Y = selling price of the condo in dollars
x1 = sqaure footage of living are
x2 = size of garage, in number of cars
x3 = age of condo, in years
x4 = dummy variable taking the value 1 if the condo has a fireplace and 0 otherwise
x5 = dummy variable taking the value 1 if the condo has hardwood floors and 0 if it has vinyl floors
a. Interpret the estimated coefficient of x4.
b. Interpret the estimated coefficient of x5.
c. Find a 95% confidence interval for the impact of a fireplace on selling price, all other things being equal.
d. Test the null hypothesis that type of flooring has no impact on selling price against the alternative that, all other things being equal, condos with hardwood floors have a higher selling price than those with vinyl flooring.