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Answer:
1. b
2. For each 1000 miles driven, (a) saves 10.9 gallons, while (b) saves 19.8 gallons
Step-by-step explanation:
The fuel savings will depend on the miles driven. If we use 1000 miles as the reference, the various vehicle fuel usages are ...
gallons = miles/(miles/gallon)
18 mpg: 1000/18 = 55.6 gallons
28 mpg: 1000/28 = 35.7 gallons
34 mpg: 1000/34 = 29.4 gallons
54 mpg: 1000/54 = 18.5 gallons
So, ...
replacing 34 mpg with 54 mpg saves 29.4 -18.5 = 10.9 gallons.
replacing 18 mpg with 28 mpg saves 55.6 -35.7 ≈ 19.8 gallons.
Replacing the SUV with a sedan saves more fuel, assuming all vehicles are driven the same distance.
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The fuel use reduction from 18 mpg to 28 mpg is about 36%, whereas from 34 mpg to 54 mpg. the reduction is about 37%. The SUV replacement is a better choice because the smaller fraction of a much larger fuel use is still more savings than obtained by replacing the compact car.
