Chapter 4.2, Problem 9P

Weight of Car: Miles per Gallon Do heavier cars really use more gasoline? Suppose a car is chosen at random. Let x be the weight of the car (in hundreds of pounds), and let y be the miles per gallon (mpg). The following information is based on data taken from Consumer Reports (Vol. 62, No. 4).

x	27	44	32	47	23	40	34	52
y	30	19	24	13	29	17	21	14

Complete parts (a) through (e), given ${\displaystyle \sum x}=299,{\displaystyle \sum y=167,{\displaystyle \sum x^2=11,887,{\displaystyle \sum y^2=3773,{\displaystyle \sum xy=5814,\text{and}r\approx -\mathrm{0.946.}}}}}$

(f) Suppose a car weighs $x=38$ (hundred pounds). What does the least-squares line forecast for y = miles per gallon?