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# M15-13

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Math Expert
Joined: 02 Sep 2009
Posts: 54376

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16 Sep 2014, 00:55
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Difficulty:

25% (medium)

Question Stats:

72% (00:57) correct 28% (01:20) wrong based on 101 sessions

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Two engines were tested to determine their fuel consumption rate. If during the test, the first engine consumed 600 grams of fuel while the second, which worked for two hours less, consumed 384 grams, how much fuel will be required to run the second engine for 5 hours?

(1) The first engine worked for 10 hours during the test.

(2) If the first engine had worked for 2 more hours during the test, it would have consumed 120 grams of fuel more.

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16 Sep 2014, 00:55
Official Solution:

Statement (1) by itself is sufficient. We have to know the consumption rate of the second engine. This rate = $$\frac{384}{t - 2}$$ where $$t$$ is the time the first engine worked during the test. From S1 we know $$t$$ and thus we can answer the question.

Statement (2) by itself is sufficient. From S2 we know that the first engine consumes 60 grams of fuel each hour. Therefore, $$\frac{600}{t} = 60$$ from where $$t = 10$$.

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29 May 2015, 16:34
How are we able to determine the consumption rate of the second engine from the consumption rate of the first engine? The statements 1 and 2 and the question stem doesn't provide any relationship between the first engine and the second engine.
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30 May 2015, 04:03
geocopi wrote:
How are we able to determine the consumption rate of the second engine from the consumption rate of the first engine? The statements 1 and 2 and the question stem doesn't provide any relationship between the first engine and the second engine.

"the first engine consumed 600 grams of fuel while the second, which worked for two hours less, consumed 384 grams"
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30 May 2015, 04:37
Thank you for responding to a silly question.
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Joined: 02 Sep 2014
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GMAT 1: 770 Q50 V44
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10 Feb 2016, 23:39
Arent we assuming the consumption rate is constant? if A runs 2 more hours then the increase in consumption is assumed linear.
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11 Feb 2016, 04:39
82vkgmat wrote:
Arent we assuming the consumption rate is constant? if A runs 2 more hours then the increase in consumption is assumed linear.

Hi,
you can not assume that the consumption rate is constant..

If the consumption rate had been constant, we didn't require any additional info to answer the question, as answer was there within the Q onle..
600 normal.. 384 for 2 hours less...
so 600-384 is consumed in two hours..
216/2 =108 per hour..
108*5 for 5 hours...
Assuming what you have said we didnot require the statements..

hope it helps
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14 Jul 2017, 10:48
Hi chetan,
What you're suggesting with the above explanation is that A and B have same rate of fuel consumption. The question pointed out was whether A's and B's fuel consumption rate (independent of each other) is constant for every hour. because that is what the question assumes so, but it's not pointed out..

Let me know if im wrong.
Re: M15-13   [#permalink] 14 Jul 2017, 10:48
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# M15-13

Moderators: chetan2u, Bunuel

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