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# If 5 engines consume 6 metric tonnes of coal when each is running for

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Math Expert
Joined: 02 Sep 2009
Posts: 62348
If 5 engines consume 6 metric tonnes of coal when each is running for  [#permalink]

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28 Dec 2019, 00:38
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Difficulty:

65% (hard)

Question Stats:

59% (02:26) correct 41% (02:53) wrong based on 54 sessions

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If 5 engines consume 6 metric tonnes of coal when each is running for 9 hours a day, how many metric tonnes of coal will be needed for 8 engines, each running 10 hours a day, given that 3 engines of the former type consume as much as 4 engines of the latter type.

A. 8
B. 9
C. 12
D. 12.5
E. 14.2

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Joined: 18 Aug 2017
Posts: 6058
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: If 5 engines consume 6 metric tonnes of coal when each is running for  [#permalink]

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28 Dec 2019, 05:38
Bunuel wrote:
If 5 engines consume 6 metric tonnes of coal when each is running for 9 hours a day, how many metric tonnes of coal will be needed for 8 engines, each running 10 hours a day, given that 3 engines of the former type consume as much as 4 engines of the latter type.

A. 8
B. 9
C. 12
D. 12.5
E. 14.2

use
m1*t1/w1 = m2*t2/w2
solve w2 = 8*3/4
and given then given that 3 engines of the former type consume as much as 4 engines of the latter type.
so answer IMO A ; 8
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3337
Re: If 5 engines consume 6 metric tonnes of coal when each is running for  [#permalink]

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29 Dec 2019, 04:09

Solution

Given
• 5 engines consume 6 metric tonnes of coal when each is running for 9 hours a day
• 3 engines of the former type consume as much as 4 engines of the latter type

To find
• How many metric tonnes of coal will be needed for 8 engines, each running 10 hours a day?

Approach and Working out
We have:
• Direct relation between engine and coal: more engine – more coal
• Direct relation between hours and coal: more hours per day – more coal
• Direct relation between rate of consumption and coal: more consumption – more coal

Ratio of engines = 5: 8
Ratio of hours per day = 9: 10
Ratio of consumption rate = (1/3): (1/4)
These ratios are equal to 6: n

Therefore,
• n = 8 x 10 x ¼ x 6 x 1/5 x 1/9 x 3
Or, n = 8

Thus, option A is the correct answer.

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Joined: 17 Jan 2020
Posts: 2
Location: United Kingdom
Concentration: Healthcare, General Management
WE: Science (Health Care)
Re: If 5 engines consume 6 metric tonnes of coal when each is running for  [#permalink]

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07 Feb 2020, 04:11
EgmatQuantExpert wrote:

Solution

Given
• 5 engines consume 6 metric tonnes of coal when each is running for 9 hours a day
• 3 engines of the former type consume as much as 4 engines of the latter type

To find
• How many metric tonnes of coal will be needed for 8 engines, each running 10 hours a day?

Approach and Working out
We have:
• Direct relation between engine and coal: more engine – more coal
• Direct relation between hours and coal: more hours per day – more coal
• Direct relation between rate of consumption and coal: more consumption – more coal

Ratio of engines = 5: 8
Ratio of hours per day = 9: 10
Ratio of consumption rate = (1/3): (1/4)
These ratios are equal to 6: n

Therefore,
• n = 8 x 10 x ¼ x 6 x 1/5 x 1/9 x 3
Or, n = 8

Thus, option A is the correct answer.

Hi Payal,

Could you elaborate how you got the consumption rate?

Thanks,
Intern
Joined: 15 Oct 2019
Posts: 15
Re: If 5 engines consume 6 metric tonnes of coal when each is running for  [#permalink]

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08 Feb 2020, 08:46
Bunuel wrote:
If 5 engines consume 6 metric tonnes of coal when each is running for 9 hours a day, how many metric tonnes of coal will be needed for 8 engines, each running 10 hours a day, given that 3 engines of the former type consume as much as 4 engines of the latter type.

A. 8
B. 9
C. 12
D. 12.5
E. 14.2

Hi Bunuel,

Are these types of questions asked in actual GMAT ? If yes, I request you to please provide an easier approach solution.

Thanks,
Ankit Singh
Re: If 5 engines consume 6 metric tonnes of coal when each is running for   [#permalink] 08 Feb 2020, 08:46
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