Letxbe the size of a house (in square feet) andybe the amount of natural gas used (therms) during a specified period. Suppose that for a particular community,xandyare related according to the simple linear regression model with the following values.

= slope of population regression line =0.013

=yintercept of population regression line=5

(a) What is the equation of the population regression line?

y=

(b) What is the mean value of gas usage for houses with2100sq. ft. of space?

(c) What is the average change in usage associated with a 1 sq. ft. increase in size?

(d) What is the average change in usage associated with a 100 sq. ft. increase in size?