Aptitude - Pipes and Cistern - Discussion

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"Nothing is impossible to a willing heart."

- (Proverb)

A pump can fill a tank with water in 2 hours. Because of la leak, it took 2 hours to fill the tank. The leak can drain all the water of the tank in:

[A].

4	1	hours
	3

[B].

7 hours

[C].

8 hours

[D].

14 hours

Answer: Option A

Explanation:

Work done by the leak in 1 hour = 1 - 3 = 1 .

2 7 14

Leak will empty the tank in 14 hrs.

Priyanka Sharma said: (Wed, Nov 17, 2010 08:25:30 PM)

Please tell how it is (1/2 - 3/7) ?

Paushali Mukhoty said: (Thu, Dec 30, 2010 03:02:19 PM)

If the total area of pump=1 part The pumop take 2 hrs to fill 1 part The pumop take1 hour to fill 1/2 portion Due to lickage The pumop take 7/3 hrs to fill 1 part The pumop take1 hour to fill 3/7 portion Now the difference of area = (1/2-3/7)=1/14 This 1/14 part of water drains in 1 hour Total area=1 part of water drains in (1x14/1)hours= 14 hours So the leak can drain all the water of the tank in 14 hours.

Jad1980 said: (Fri, Feb 18, 2011 11:11:46 AM)

I'm confused, please check my logic 1. It takes 2 hours for the pump to fill the tank without the leak. 2. The leak adds 1/3hrs onto that time time, which is an increase in time of 1/6th. 3. Then the amount leaked = 1/6 of the amount pumped. 4. When the pumped is turned off the leak will drain the tank at 1/6 of the speed at which the pump fills it 5. If it takes the pump 2hrs to fill it then it should take 12 hours for the leak to drain the tank

Sandeep said: (Mon, May 23, 2011 07:32:13 AM)

Paushali Mukhoty Good explanation thank you.

Vivek said: (Tue, Jul 5, 2011 09:44:31 AM)

Nice explanation by Paushali Mukhoty.

Krunal said: (Mon, Aug 8, 2011 12:34:49 AM)

Very well explaination. I understand very well.

Amitha said: (Tue, Sep 6, 2011 08:23:04 PM)

How cum 7/3 hours to fill 1 part for the leakage?

Radhika Krishna said: (Mon, Sep 12, 2011 05:26:21 PM)

Their total tank divided in to 7 parts i.e 20 min to fill 1/3min to fill 1 part

Zakeer said: (Thu, Oct 27, 2011 03:16:50 PM)

How come 7/3 hours to fill 1 part for the leakage?

Pgcr ( Sri Lanka) said: (Fri, Nov 4, 2011 09:20:06 AM)

Just because of the leak it took 2 1/3 hours. Normally it takes only 2 hours. Hence, 1 1 1 - - - = - 2 X (2 1/3) OR 1 1 1 - - - = - 2 (2 1/3) X So, X = 14 hours.

Chakri said: (Thu, Jan 5, 2012 08:22:32 PM)

Please tell me why it's 7/3 changed into 3/7?

Ashu said: (Fri, Jan 13, 2012 06:16:43 PM)

@chakri If you take 7/3 hrs to complete 1 job Then, what length of job will you take to complete in 1 hour ( what you do here is...use reciprocal value when u shift the value) that is 7/3=>1 1=>3/7

Ashu said: (Fri, Jan 13, 2012 06:18:12 PM)

PGCR great logic. What type of logic you used here? Please explain.

Deepi said: (Sun, Feb 5, 2012 07:17:57 PM)

A takes 2 hrs lets take as x Leakage time lets y 2 1/3 hrs=7/3hrs => (x*y)/(y-x)=7/3 => (2y)/(y-2)=7/3 => 2y=(y-2)(7/3) => 2y=(7y/3)-14/3 => -y/3=-14/3 => y=14