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

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Intern
Joined: 29 Mar 2014
Posts: 14
A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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21 Feb 2015, 12:04
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5% (low)

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93% (01:08) correct 7% (02:01) wrong based on 202 sessions

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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

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?
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Joined: 02 Sep 2009
Posts: 58391
Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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21 Feb 2015, 12:24
pinkcupcake 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

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?

240/10 = 24, not 25. The difference is 24 - 20 = 4.
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Intern
Joined: 29 Mar 2014
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Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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21 Feb 2015, 12:28
Bunuel wrote:
pinkcupcake 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

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?

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

what a silly embarrassing mistake I made, thank you Bunuel!
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Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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21 Feb 2015, 12:33
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
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Joined: 25 Apr 2013
Posts: 56
Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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22 Feb 2015, 10:40
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:).
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Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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13 Oct 2016, 07:59
1
pinkcupcake 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

Quote:
12 gallons of gasoline in traveling 240 miles.

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

Mileage = 20 miles/gallon

Quote:
by how many miles per gallon must the car’s gas mileage be increased to travel the same distance using 10 gallons of gasoline

$$Mileage = \frac{Distance}{Gasoline}$$

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

So, $$200 + 10x = 240$$

Or, $$x = 4$$

Hence answer will be (B) 4
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Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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14 Oct 2016, 05:44
1
pinkcupcake 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.

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Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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19 Feb 2018, 09:43
pinkcupcake 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

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?

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

Intern
Joined: 03 Jun 2013
Posts: 18
Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.  [#permalink]

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10 Oct 2018, 04:17
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
Re: A certain car uses 12 gallons of gasoline in traveling 240 miles.   [#permalink] 10 Oct 2018, 04:17
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# A certain car uses 12 gallons of gasoline in traveling 240 miles.

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