It is currently 20 Oct 2017, 07:02

### 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
Current Student
Joined: 11 May 2008
Posts: 555

Kudos [?]: 222 [0], given: 0

Working together at their respective rates, machine A, B, [#permalink]

### Show Tags

22 Jul 2008, 11:46
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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.

Kudos [?]: 222 [0], given: 0

Intern
Joined: 08 Jul 2008
Posts: 14

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

### Show Tags

22 Jul 2008, 12:00
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

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

SVP
Joined: 28 Dec 2005
Posts: 1545

Kudos [?]: 179 [0], given: 2

### Show Tags

22 Jul 2008, 15:27
B for me as well, same reasoning as above

Kudos [?]: 179 [0], given: 2

Director
Joined: 12 Jul 2008
Posts: 514

Kudos [?]: 162 [0], given: 0

Schools: Wharton

### Show Tags

22 Jul 2008, 15:39
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

Kudos [?]: 162 [0], given: 0

Re: work and time   [#permalink] 22 Jul 2008, 15:39
Display posts from previous: Sort by