Aptitude - Pipes and Cistern - Discussion

@Paushali Mukhtoy is very well explained. Thank you.

For inlet it takes one hour for 1/2 part. For leakage, let's consider it takes 1 hour for 1/x parts.

For 2 hours and 20 minutes the tank will be filled as question says: (1/2-1/X)*7/3 = 1 (the full tank having 1 part).

@Mouni.

Please check this one:

Let us take Cistern is filled by pipe A and leak is due to pipe B (In this way it is easy to understand).

First point : Cistern filled by pipe A in 8 hrs.

Second point : Cistern filled by pipe A and pipe B (it is actually leak) is 10hrs (8+2).

Now take LCM of these two LCM of 8, 10 is 40. This implies to fill Cistern, total 40 units of work needed.

Then if only pipe A can fill the Cistern in 8 hrs that means 5 units of work for min by pipe A. Both pipe A and pipe B can fill the Cistern in 10 hrs that means 4 units of work by pipe A and pipe B.

So if you see, in second case 4 units of work per min where as in first case it is 5 units of work. This means if you include leak it reduces the work units by 1 unit ---> leakage per hr is 1 unit.

So to drain all the water in cistern, leak has to do 40 units of work. So if it is doing 1 unit of work to drain the tank. For 40 units it has to 40 hrs of work. So answer : 40 hrs.

A cistern is normally filled in 8 hrs. But takes 2 hrs more to fill because of a leak in its bottom. If the cistern is full, the tank will empty it in?

Please tell me with explanation.

I can't understand how 7/3 is converts in to 3/7?

/*Other method to solve this problem */.

A, A-l.

Time 120, 140.

Time/min 7, 6.

Capacity 840, 840 of tank.

So due to leakage difference in time/min (7-6) = 1.

So 840/1 = 840 min.

Convert it in hr.

= 840/60 = 14 hr.

& This is our require answer.

For those who didn't got that how 7/3 come from?

Here it is 2*1/3 hours means (2*3+1)/3 = 7/3.

I had one doubt if suppose they are asking to find when the tank is filled due to its leakage means how to solve it? Please can anyone explain?

A pump can fill a tank with water in 2 hours. Because of a leak, it took 2 hours to fill the tank. No where it is written that its taking 2.20 mints to fill while after leakage. Then why everyone taking (7/3). I am lost. Do help.

@PGCR.

Very well explained. Thank you :).