A certain car uses 12 gallons of gasoline in traveling 240 miles.

Question

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

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

I took the approach as 12 gallons/240 miles = 1 gallon per 20 miles and 10 gallons/240 miles = 1 gallon/ 25 miles. Then i got stuck, can anyone please tell me what I am doing wrong or why my approach is wrong please?

Bunuel · Answer

240/10 = 24, not 25. The difference is 24 - 20 = 4.

pinkcupcake · Answer

what a silly embarrassing mistake I made, thank you Bunuel!

Celestial09 · Answer

IMO B

240 /20 = 20 miles per gallon
240/10= 24 miles per gallon
extra miles needed per gallon = 24-20 = 4 miles per gallon
hence B
Thanks
Celestial

Kudos if its a correct approach

damyanti · Answer

This does seem to be a sub 600 level question; in fact so simple that I had to think long whether there was any catch:).

Abhishek009 · Answer

12 gallons of gasoline------ traveling 240 miles
1 gallons of gasoline------ traveling 20 miles

Mileage = 20 miles/gallon

Mileage = \frac{Distance}{Gasoline}

20+ x = \frac{240}{10}

So,  200 + 10x = 240

Or,  x = 4

Hence answer will be (B) 4

ScottTargetTestPrep · Answer

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

dave13 · Answer

here is my solution

240/12 = 20 miles per 1 gallon 240/10 = 24 miles per 1 gallon hence by 4 more miles per gallon mileage should be increased

Subhrajyoti · Answer

In 18 gallons= 270 miles, therefore 1 gallon= 270/18 miles, thus in 10 gallons = (270*10)/18= 150 miles. Diffrential is 270-150= 120. Thus to cover 120 miles in 10 gallons you need 120/10= 12 miles extra mileage to be kicked in for us to cover 270 miles

PolarisTestPrep · Answer

Hey,

So you are told that the car travels 240 miles on 12 gallons of gas

Put this in equation form:

\frac{240}{12} = 20  miles per gallon

Next we want to know what the gas mileage would be if it travelled the same distance on 10 gallons of gas

Set up the equation again:

\frac{240}{10}= 24  miles per gallon

Ultimately the question is asking by how much the miles per gallon has to increase for it to travel the same distance as before with 10 gallons of gas

Subtract to find the difference:

24 - 20 = 4

The answer is B

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A certain car uses 12 gallons of gasoline in traveling 240 miles.

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