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# Machines A, B, and C can either load nails into a bin or unload nails

Author Message
TAGS:
Manager
Joined: 22 Jul 2008
Posts: 95
Location: Bangalore,Karnataka
Followers: 3

Kudos [?]: 95 [0], given: 11

Machines A, B, and C can either load nails into a bin or unload nails [#permalink]  30 Nov 2009, 06:57
00:00

Difficulty:

(N/A)

Question Stats:

89% (03:13) correct 11% (02:11) wrong based on 63 sessions

(A) 12 minutes
(B) 15 minutes
(C) 18 minutes
(D) 36 minutes
(E) 54 minutes

OPE DISCUSSION OF THIS QUESTION IS HERE: machines-a-b-and-c-can-either-load-nails-into-a-bin-or-86031.html

Last edited by kirankp on 30 Nov 2009, 08:01, edited 1 time in total.
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VP
Joined: 05 Mar 2008
Posts: 1473
Followers: 11

Kudos [?]: 224 [1] , given: 31

Re: Machines A, B, and C can either load nails into a bin or unload nails [#permalink]  30 Nov 2009, 07:18
1
KUDOS
1
This post was
BOOKMARKED
kirankp wrote:
I guess a similar question was posted by Bunel sometime back.. anyhow here it is

(A) 12 minutes
(B) 15 minutes
(C) 18 minutes
(D) 36 minutes
(E) 54 minutes

A and B together = 1/a + 1/b = 1/6

B and C together = 1/b + 1/c = 1/9

We need to know the answer to 1/a - 1/c

From equation 2: 1/b = 1/9 - 1/c
substitute into equation 1

1/a + 1/9 - 1/c = 1/6
1/a - 1/c = 1/18

18 minutes
Senior Manager
Joined: 15 Sep 2011
Posts: 306
Location: United States
WE: Corporate Finance (Manufacturing)
Followers: 4

Kudos [?]: 169 [1] , given: 40

Re: Machines A, B, and C can either load nails into a bin or unload nails [#permalink]  25 Jun 2015, 07:42
1
KUDOS
kirankp wrote:
I guess a similar question was posted by Bunuel sometime back.. anyhow here it is

(A) 12 minutes
(B) 15 minutes
(C) 18 minutes
(D) 36 minutes
(E) 54 minutes

Bumping up. Moderator should edit in answer.
$$\frac{1}{6}$$ - $$\frac{1}{9}$$ = $$\frac{1}{18}$$
D. 18 minutes.

This works because $$\frac{a+b}{ab}$$ - $$\frac{b+c}{bc}$$ = $$\frac{c-a}{ac}$$ and $$\frac{1}{a}$$ - $$\frac{1}{c}$$ = $$\frac{c-a}{ac}$$
Math Expert
Joined: 02 Sep 2009
Posts: 29205
Followers: 4751

Kudos [?]: 50274 [0], given: 7540

Re: Machines A, B, and C can either load nails into a bin or unload nails [#permalink]  25 Jun 2015, 07:47
Expert's post
OPE DISCUSSION OF THIS QUESTION IS HERE: machines-a-b-and-c-can-either-load-nails-into-a-bin-or-86031.html
_________________
Verbal Forum Moderator
Joined: 02 Aug 2009
Posts: 1230
Followers: 27

Kudos [?]: 511 [0], given: 19

Re: Machines A, B, and C can either load nails into a bin or unload nails [#permalink]  25 Jun 2015, 07:49
mejia401 wrote:
kirankp wrote:
I guess a similar question was posted by Bunuel sometime back.. anyhow here it is

(A) 12 minutes
(B) 15 minutes
(C) 18 minutes
(D) 36 minutes
(E) 54 minutes

Bumping up. Moderator should edit in answer.
$$\frac{1}{6}$$ - $$\frac{1}{9}$$ = $$\frac{1}{18}$$
D. 18 minutes.

This works because $$\frac{a+b}{ab}$$ - $$\frac{b+c}{bc}$$ = $$\frac{c-a}{ac}$$ and $$\frac{1}{a}$$ - $$\frac{1}{c}$$ = $$\frac{c-a}{ac}$$

Ans is ok as it is it is C which is 18 and D is 36...
Re: Machines A, B, and C can either load nails into a bin or unload nails   [#permalink] 25 Jun 2015, 07:49
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