How to go about this problem

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How to go about this problem

by timbo » Fri Jul 17, 2009 4:58 am
A certain car uses 12 gallons of gasoline in traveling 240 miles. In order for the car to travel the same distance using 10 gallons of gasoline, by how many miles per gallon must the car's gas mileage be increased?

(A) 2 (B) 4 (C) 6 (D) 8 (E) 10

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by struggling_guy2001 » Fri Jul 17, 2009 5:31 am
A certain car uses 12 gallons of gasoline in traveling 240 miles.

==> mileage is (240/12) = 20 miles for gallon.

same distance using 10 gallons of gasoline

===> mileage shoud be (240/10) = 24 miles per gallon.

by how many miles per gallon must the car's gas mileage be increased?

Hence mileage should be increased by 4 miles per gallon.

Ans is B.
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by Scott@TargetTestPrep » Tue Dec 05, 2017 5:13 pm
timbo wrote:A certain car uses 12 gallons of gasoline in traveling 240 miles. In order for the car to travel the same distance using 10 gallons of gasoline, by how many miles per gallon must the car's gas mileage be increased?

(A) 2 (B) 4 (C) 6 (D) 8 (E) 10
We are given that a certain car uses 12 gallons of gasoline in traveling 240 miles.

Since rate = distance/gallons used, the rate of the car, in miles per gallon, is 240/12 = 20 mpg.
If the car were to travel the same distance using 10 gallons of gasoline, the rate, in miles per gallon, would be 240/10 = 24.

Thus, the new rate is 4 mpg more than that of the old rate.

Answer: B

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