Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 07 Jul 2015, 08:05

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Working together at their respective rates, machine A, B,

Author Message
TAGS:
Current Student
Joined: 11 May 2008
Posts: 560
Followers: 7

Kudos [?]: 59 [0], given: 0

Working together at their respective rates, machine A, B, [#permalink]  22 Jul 2008, 10:46
Working together at their respective rates, machine A, B, and C can finish a certain work in 8/3 hours. How many hours will it take A to finish the work independently?
(1) Working together, A and B can finish the work in 4 hours.
(2) Working together, B and C can finish the work in 48/7 hours.
Intern
Joined: 08 Jul 2008
Posts: 14
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: work and time [#permalink]  22 Jul 2008, 11:00
given 1/A + 1/B+1/C = 3/8 [1]
find A:

1st statement is not sufficient as we ve 1/A + 1/B = 1/4 , we don't ve the value of 1/C so that we can substitute in in [1]

2nd statement is sufficient as we have 1/B + 1/C = 7/48, We can subsitute this in equation [1] and find the value of a:
1/A + 7/48 = 3/8
=> 1/A = 11/48
=> A = 48/11
SVP
Joined: 28 Dec 2005
Posts: 1578
Followers: 2

Kudos [?]: 91 [0], given: 2

Re: work and time [#permalink]  22 Jul 2008, 14:27
B for me as well, same reasoning as above
Director
Joined: 12 Jul 2008
Posts: 518
Schools: Wharton
Followers: 16

Kudos [?]: 122 [0], given: 0

Re: work and time [#permalink]  22 Jul 2008, 14:39
RayOfLight wrote:
given 1/A + 1/B+1/C = 3/8 [1]
find A:

1st statement is not sufficient as we ve 1/A + 1/B = 1/4 , we don't ve the value of 1/C so that we can substitute in in [1]

2nd statement is sufficient as we have 1/B + 1/C = 7/48, We can subsitute this in equation [1] and find the value of a:
1/A + 7/48 = 3/8
=> 1/A = 11/48
=> A = 48/11

I get B, but with a different reasoning:

1:
1/A + 1/B = 1/4
1/A + 1/B + 1/C = 3/8
1/4 + 1/C = 3/8
1/C = 1/8

1/A + 1/B + 1/8 = 3/8 -- now you're stuck because you don't know the ratio of A:B or the value of B.

2:
1/A + 1/B + 1/C = 3/8
1/A + 7/48 = 3/8
1/A = 11/48
A = 48/11
Re: work and time   [#permalink] 22 Jul 2008, 14:39
Similar topics Replies Last post
Similar
Topics:
Machines X and Y work at their respective constant rates. 3 31 Aug 2008, 10:52
working together at their constant rates , A and B can fill 6 18 Jul 2008, 05:08
Machines X and Y work at their respective constant rates. 7 14 Jun 2007, 23:13
Machines X and Y work at their respective constant rates. 19 02 May 2006, 20:43
1 6 machines, all working at a constant rate, together can do 5 10 Oct 2005, 06:49
Display posts from previous: Sort by