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# Six machines each working at the same

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VP
Joined: 18 May 2008
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Six machines each working at the same [#permalink]  13 Nov 2008, 02:46
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Manager
Joined: 08 Aug 2008
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Re: GMATCLUB- machines [#permalink]  13 Nov 2008, 06:29
more workers, lesser days....(inverse ratio since rates are same..)
6/x=8/12==> x=9

so 9-6 =3 additional workers reqd.
Manager
Joined: 23 Jul 2008
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Re: GMATCLUB- machines [#permalink]  13 Nov 2008, 11:19
using unitary method
six m/cs------12 days
one m/cs------72 days
nine m/cs------8 days
Director
Joined: 14 Aug 2007
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Re: GMATCLUB- machines [#permalink]  13 Nov 2008, 19:07
6 machines * Rate of individual machine (R) * 12 days = 1 work

Therefore R = 1/72

Let X be the total number of machines reqd to complete work in 8 days

we have,

X * 1/72 * 8 = 1

X =9

we need to know how many "additional" machines are reqd = 9 -6 = 3
VP
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Re: GMATCLUB- machines [#permalink]  13 Nov 2008, 20:30
Ohhhhhhhhhhhh. I didnt notice the word "additional" in the question and got 6 as the final answer.
This shows we shld read wht exactly is required in the question
Director
Joined: 14 Aug 2007
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Re: GMATCLUB- machines [#permalink]  13 Nov 2008, 20:47
ritula wrote:
Ohhhhhhhhhhhh. I didnt notice the word "additional" in the question and got 6 as the final answer.
This shows we shld read wht exactly is required in the question

But then you should get 9 as answer right
or was it an upside down problem (9 6)
Re: GMATCLUB- machines   [#permalink] 13 Nov 2008, 20:47
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