Question

suppose a new car travels 70.0 miles on one gallon of gasoline with 40% efficient engine.
how much fuel is wasted annually due to energy efficiency if in one yr, 478.26 gallons of fuel is burned?

Answer 1

286.956 gallons!

70 - (40% of 70) = 42 = wasted fuel

set up a proportion

70/42 = 478.26/x

x= 286.956

im pretty sure that's how u do it...but not postivie...so check w. other resources!!!

Answer 2

I wouldn't do it that way.
Fuel burned in 1 yr = 478.26 gallons.
We wasted 40% or 0.4.
478.26 gal x 0.4 = 191.3 gal wasted.
[In the first answer by Tarun, the 70 - (40% of 70) = 42 is the 60% which is used, not the 40% which is wasted.

You can also do it another way.
70 mi/gal x 478.26 gal x 1.00 = 33,478.20 miles if 100% efficient.
70 mi/gal x 478.26 gal x 0.60 = 20,086.92 miles if 60% effecient.
The difference is 13,391.28 miles, which if the car was 100% efficient, would be 13,391.28/70 = 191.3 gallons wasted.