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

 It is currently 04 May 2015, 18:47

### 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

# A swimming pool has three pumps, A, B and C. Working

Author Message
TAGS:
GMAT Instructor
Joined: 04 Jul 2006
Posts: 1269
Followers: 23

Kudos [?]: 158 [0], given: 0

A swimming pool has three pumps, A, B and C. Working [#permalink]  14 Sep 2006, 13:22
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
A swimming pool has three pumps, A, B and C. Working together at their constant rates, A and B can drain the swimming pool in 10 hours, whereas A and C can drain the pool in 12 hours. How long does it take A to drain the pool?

(1) B and C, working together, can drain the pool in 15 hours.
(2) The time it would take 3 B's to drain the pool is equal to the time it would take 4 C's to do so.

Last edited by kevincan on 14 Sep 2006, 13:42, edited 1 time in total.
SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

In statment (1), is it A C working together or B C ?
SVP
Joined: 24 Aug 2006
Posts: 2134
Followers: 3

Kudos [?]: 98 [0], given: 0

Re: DS: Swimming Pool Drainage [#permalink]  14 Sep 2006, 13:56
kevincan wrote:
A swimming pool has three pumps, A, B and C. Working together at their constant rates, A and B can drain the swimming pool in 10 hours, whereas A and C can drain the pool in 12 hours. How long does it take A to drain the pool?

(1) B and C, working together, can drain the pool in 15 hours.
(2) The time it would take 3 B's to drain the pool is equal to the time it would take 4 C's to do so.

I will explain later. B gets tricky.
SVP
Joined: 24 Aug 2006
Posts: 2134
Followers: 3

Kudos [?]: 98 [0], given: 0

Re: DS: Swimming Pool Drainage [#permalink]  14 Sep 2006, 17:44
kidderek wrote:
kevincan wrote:
A swimming pool has three pumps, A, B and C. Working together at their constant rates, A and B can drain the swimming pool in 10 hours, whereas A and C can drain the pool in 12 hours. How long does it take A to drain the pool?

(1) B and C, working together, can drain the pool in 15 hours.
(2) The time it would take 3 B's to drain the pool is equal to the time it would take 4 C's to do so.

I will explain later. B gets tricky.

Hmmm, I might be over thinking, but I am going to retract the D answer and get back to it.
VP
Joined: 02 Jun 2006
Posts: 1267
Followers: 2

Kudos [?]: 42 [0], given: 0

Given
Ra = 1/Ta
Rb = 1/Tb
Rc = 1/Tc

Where Ta, Tb & Tc are times to drain the pool by themselves.

Given
Ra + Rb = 1/10 .... (1)

Rb + Rc = 1/12 ... (2)

=> Rb -Rc = 1/60 .... (3)

S1:
Rb + Rc = 1/15

From (3) and above eqn we can find Rb.

From Rb and (1) we can find Ra.
Sufficient.

S2:
3Rb = 4Rc

3Rb - 4Rc = 0

From (2) multiplying by 4:

4Rb +4Rc = 1/3
3Rb -4Rc = 0

Can solve for Rb... and from (1) can solve for Ra.

Sufficient.

Director
Joined: 23 Jun 2005
Posts: 847
GMAT 1: 740 Q48 V42
Followers: 5

Kudos [?]: 31 [0], given: 1

Arrived at D, but didn't work it out as detailed as Haas_mba07.
Statement 1: Gives you B+C. Imagine 2As, 1 B and 1 C [(A+B) and (A+C)] draining the tank and two more pumps (B+C) pouring in water, and you effectively negate B and C and can figure out how long it takes A to drain the tank. So, sufficient.
Statement 2: Gives you B in terms of C or vice versa. Substitute appropriately to find out A.

Wow! Typing this out took much longer than figuring it out in my head. Hope it makes sense to most people at least.
Manager
Joined: 13 Sep 2006
Posts: 212
Followers: 2

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

D..for this reason...

1 and 2 result in 3 equations w/ 3 distinct variables.
Intern
Joined: 27 Aug 2006
Posts: 32
Followers: 0

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

Hass_Mba or Anyone,

Pardon my lack of knowledge ,but how did u get to #3 Higlighted below

--Snippet from solution earlier
Given
Ra = 1/Ta
Rb = 1/Tb
Rc = 1/Tc

Where Ta, Tb & Tc are times to drain the pool by themselves.

Given
Ra + Rb = 1/10 .... (1)

Rb + Rc = 1/12 ... (2)

=> Rb -Rc = 1/60 .... (3)

could u pls explain ?
thanks
Similar topics Replies Last post
Similar
Topics:
8 Working alone, pump A can empty a pool in 3 hours. Working alone, pump 10 23 Mar 2015, 05:34
3 A, B and C start swimming in a pool simultaneously from the 5 09 Mar 2014, 21:31
2 Pump A can empty a pool in A minutes, and pump B can empty 8 24 Jan 2014, 06:13
13 Marge has 3 pumps for filling her swimming pool. When all 3 6 10 Feb 2013, 06:11
1 Working together, 7 identical pumps can empty a pool in 6 5 17 Oct 2012, 20:32
Display posts from previous: Sort by