Need help with C, E & F

Do heavier cars really use more gasoline? Suppose a car is chosen at random. Letxbe the weight of the car (in hundreds of pounds), and letybe the miles per gallon (mpg).

x: 30 46 33 47 23 40 34 52

y: 29 19 23 13 29 17 21 14

Complete parts (a) through (e), given x=305,y=165,x²=12,303,y²=3667,xy=5903,andr0.919.

(b) Verify the given sumsx,y,x²,y²,xy, and the value of the sample correlation coefficientr. (Round your value forrto three decimal places.)

x=

y=

x²=

y²=

xy=r=

(c) Findx, andy. Then find the equation of the least-squares line=a+bx. (Round your answers forxandyto two decimal places. Round your answers foraandbto three decimal places.)

x=

y=

y= ___+___x

(e) Find the value of the coefficient of determinationr². What percentage of the variation inycan beexplainedby the corresponding variation inxand the least-squares line? What percentage isunexplained? (Round your answer forr²to three decimal places. Round your answers for the percentages to one decimal place.)

r²= _______

explained_____%

unexplained_____%

(f) Suppose a car weighsx=30(hundred pounds). What does the least-squares line forecast fory= miles per gallon? (Round your answer to two decimal places.)

______mpg