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At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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23 Sep 2010, 14:37
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At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank? A. 3/25 B. 11/36 C. 7/12 D. 2/3 E. 25/36
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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23 Sep 2010, 14:39
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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24 Sep 2010, 16:04
Gas used = (5 hours)*(50 miles/hour)*(1 gallon/30 miles) = 8+1/3 gallons Portion used = (8+1/3) / 12 = 25/36
Ans E



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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29 Dec 2010, 05:45
Hi, Could you please advice how to solve below problem
At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours. the amount of gasoline used would be what fraction of full tank?
Thank you
Awaiting prompt reply
KD



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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29 Dec 2010, 07:53
In the given example SPEED is not mentioned with which the car traveled for 5 hrs with 12 gallons in the tank
Therefore, we have to assume that car traveled with the same speed Now we can calculate distance traveled by the car in 5 hrs = D = S*t = 50 * 5 = 250 miles
We know that car travels 30 miles in 1 gallon Therefore gallons of fuel required for 250 miles = 25/3
Hence, fraction of fuel used = 25 /3*12 = 25 / 36
But according to me something is missed out in the question, because, mostly in GMAT answers are not awkward like this.



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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26 Apr 2011, 06:44
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Gasoline used = 250/30 = 25/3 Fraction used = 25/3/12 = 25/36 Answer  E
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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30 Apr 2011, 09:32
ans is e in 5 hours car will travel 250 mile at the rate of 50 miles/hr then gasoline consumed will be \(250/30= 25/3\) => fraction of gasoline used will be (25/3) / 12 === 25/36
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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30 May 2012, 11:50
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Round off doesn't work.....250/30 is nearly 8.3 gallons..
Now 8.3/12 is not equal to 8/12(which most people who get wrong answer do) or 2/3 which is a trap and hence wrong answer...I fell in the trap,hence i know :)



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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18 Aug 2013, 19:43
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Speed  50m/h Consumption  1gallon ever 30 miles Given : 12 gallons of fuel at start Expected travel on full Tank  360m/h Actual Travel : 5 * 50 = 250 m/h
Fraction would be : 250/360 = 25/36
Ans: E



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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18 Sep 2013, 00:38
2 / 3 is trap answer. you dont need to solve beyond 25 / 8 and get ~8. let 25 / 3 remain an then divide by 12 to get 25 / 36 TomB wrote: At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A. 3/25 B. 11/36 C. 7/12 D. 2/3 E. 25/36
I am getting 2/3 .Please explain what am i missing?



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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04 Dec 2016, 03:11
Great Question Here is what i did in the one => At 50 miles/hour
Distance =250miles so => Used gas => 1/30 *250 => 25/3
Let p be the required fraction. 25/3=p*12 p=25/36
Hence E
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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05 Dec 2016, 07:49
In 5 hrs the car will travel a distance of 250 miles. 1 gallon every 30 miles equates to 25/3 gallons for 250 miles The amount of gasoline used would be (25/3)/12 = 25/36 gallon
2/3 = 0.6667 25/36 = 0.694 25/3 = 8.3 8.3/12 = 0.691 Hence E is better option than D



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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11 Apr 2017, 13:34
Kind of an extremely longwinded way to answer this question, but it's how I best visualize it is: car travels 30 miles on 1 gallon. Trip total is 250 miles. 25030=220..first gallon 22030=210..second gallon 21030=190..third gallon 19030=160..fourth gallon 16030=130..fifth gallon 13030=100..sixth gallon 10030=70..seventh gallon 7030=40..eighth gallon Left with 10 gallons which = 1/3 gallon Total of 8.3 gallons over 12 gallon tank. The smallest that can reduce down to is 2/3 so answer choices A,B & C are all out. I then crossmultiplied the remaining two answer choices and got "E". Extremely steporiented but for me it worked. Clockedin at under 2 minutes to solve, though.
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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30 May 2017, 17:26
TomB wrote: At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A. 3/25 B. 11/36 C. 7/12 D. 2/3 E. 25/36
I am getting 2/3 .Please explain what am i missing? 1.In 5 hrs the car would have traveled 250 miles. 2. It would have used 250/30 gallons 3. The car started with full tank of 12 gallons 4. Gasoline used as a fraction of full tank is (250/30)/12=25/36
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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03 Aug 2017, 05:42
I fell for the trap answer as well. I rounded off 8.3/12 which is wrong.
I used the following method to solve this:
Distance= speed x time = 50x5=250 miles
Hence, the answer E.
Using ratios, if 30 miles uses 1 gallon, how many gallons will be needed for 250 gallons?
Gallons needed= 250/30 x 1 = 25/3
Therefore, the answer will be (25/3)/12



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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06 Aug 2017, 14:36
It is important to see that all answer choices are in fraction form and hence do any calcs that way.
1 gallon = 30 miles travel
At a speed of 50 miles/hr for 5 hours , total distance travelled d = \(\frac{50miles}{hr}\)*5hrs = 250 miles
Total gasoline consumed = \(\frac{250}{30}\) = \(\frac{25}{3}\)
Total gasoline consumed as part of the total gasoline available = \(\frac{25}{3}\)*\(\frac{1}{12}\) = \(\frac{25}{36}\)



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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08 Aug 2017, 03:20
GMAT40 wrote: Speed  50m/h Consumption  1gallon ever 30 miles Given : 12 gallons of fuel at start Expected travel on full Tank  360m/h Actual Travel : 5 * 50 = 250 m/h
Fraction would be : 250/360 = 25/36
Ans: E Thanks a lot! The only option which clarified the last step of dividing by 12. This is the right way of determining the fraction of the done miles vs not done



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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09 Aug 2017, 12:49
TomB wrote: At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A. 3/25 B. 11/36 C. 7/12 D. 2/3 E. 25/36 We are given that a certain car has a rate of 30 miles per gallon if its speed is 50 mph. We are next told that the car starts with a 12gallon tank and travels for 5 hours at 50 mph. Since distance = rate x time, we know the car traveled 50 x 5 = 250 miles. We can use the car’s rate and distance traveled to determine how many gallons were used. Gallons used = distance/rate Gallons used = 250/30 = 25/3 We need to determine the amount of gasoline used, as a fraction of a full 12gallon tank. (25/3)/12 = (25/3) x (1/12) = 25/36 Answer: E
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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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27 Nov 2017, 16:11
I think I have an easier solution than what has been posted.
We know that 30mpg x 12 gallons in the tank gives us a range of 360 potential miles.
If we are traveling at 50mph for 5 hrs we thus will use 250 potential miles.
250/360 = 25/36



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Re: At a speed of 50 miles per hour, a certain car uses 1 gallon of [#permalink]
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31 Jan 2018, 13:57
Bunuel wrote: At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A. 3/25 B. 11/36 C. 7/12 D. 2/3 E. 25/36
In 5 hours at 50 miles per hour car will travel 5*50=250 miles and thus will use 250/30=25/3 gallons of gasoline. Gasoline used/full tank equals to \(\frac{(\frac{25}{3})}{12} =\frac{25}{36}\).
Answer: E. I solved the problem with the approach below and got the correct answer. Did I just get lucky? Will this not work on another similar problem? R x T = D 50mph x 5 hrs = 250 miles 12 gallons x 30 miles = 360 miles (since a car gets 1 gallon of gasoline for every 30 miles). I then just took 250 miles and divided by 360 miles then reduced down to 25/36.




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