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Pipe A runs 30 liters of water per minute into a pool that has a total

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Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 26 Aug 2015, 11:00
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Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fills a third of the pool in 6 hours.

Working together how long will it take both pipes to fill the pool?

A. 2 hours and 36 minutes
B. 1.5 hours
C. 9 hours and 12 minutes
D. 15 hours
E. 1 hour and 48 minutes.
[Reveal] Spoiler: OA

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Re: Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 27 Aug 2015, 04:26
Pool A has a rate of 30 liters per minute which equals a rate of 1800 liters per hour.
Pool B has a rate of 200 liters per hour.

200 + 1800 (A+B) = Together they have a rate of 2000 liters per hour.

3600 (The pool) / 2000 = 9/5 = 108 / 60 = 1 Hour and 48 minutes
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Re: Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 02 Sep 2015, 15:03
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- Pipe A can fill the pool in 2 hours. So its rate is 1/2.
- Pipe B can fill the pool in 18 hours. So its rate is 1/18.

Working together, Pipe A and Pipe B have a combined rate of 1/2 + 1/18 = 10/18 or 5/9 of a pool per hour. This also means that in 1 hour, both pipes can fill 5/9 of a pool.
Since t = 1/r, we learn that the time taken to fill the pool will be 9/5 hours (1h 48m) when pipes A and B work together.
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Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 02 Sep 2015, 16:00
reto wrote:
Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fills a third of the pool in 6 hours.

Working together how long will it take both pipes to fill the pool?

A. 2 hours and 36 minutes
B. 1.5 hours
C. 9 hours and 12 minutes
D. 15 hours
E. 1 hour and 48 minutes.


Using my normal intuitive method that allows my pea sized brain to process information in a more visual sort of way I did the following:

Pipe A: 30L / min = 1800L / hr
Pipe B: 1200L / 6 hr = 200L / hr
Working together: 2000L / hr

---> fill a 3000L pool in exactly 1.5hr or 3500L pool in 1.75hr

3600L is just a little bigger than 3500L so by POE I chose E. 1 hour and 48 minutes
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Re: Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 09 Nov 2017, 12:35
Pipe B takes 6 hrs to fill \(\frac{1}{3}\) rd of the tank. Hence, its rate to fill 1 tank is 18 hours.
Pipe A takes 1 min to fill 30 liters of the tank. In other words, it fills 30*60 = 1800 liters in 1 hour.
We are given that the pool capacity is 3600 liters, which means, pipe A will take 2 hours to fill it.

The combined rate is\(\frac{AB}{A+B} = \frac{2*18}{2+18} = \frac{18}{10} = 1.8\) hrs or 1 hour and 48 minutes.
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Re: Pipe A runs 30 liters of water per minute into a pool that has a total [#permalink]

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New post 10 Nov 2017, 08:45
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reto wrote:
Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fills a third of the pool in 6 hours.

Working together how long will it take both pipes to fill the pool?

A. 2 hours and 36 minutes
B. 1.5 hours
C. 9 hours and 12 minutes
D. 15 hours
E. 1 hour and 48 minutes.


Let's determine the COMBINED RATE of the two pipes

Given: Pipe A's RATE = 30 liters per minute
This is equivalent to 1800 liters per HOUR

Pipe B fills a third of the pool in 6 hours
So, Pipe B fills the ENTIRE pool (3600 liters) in 18 hours
Rate = Output/time
= 3600/18
= 200 liters per hour

COMBINED RATE = 1800 + 200
= 2000 liters per hour


Working together how long will it take both pipes to fill the pool?
Time = output/rate
= 3600/2000
= 36/20 hours
= 9/5 hours
= 1 4/5 hours
= 1 hour and 48 minutes
= E

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Re: Pipe A runs 30 liters of water per minute into a pool that has a total   [#permalink] 10 Nov 2017, 08:45
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