Aptitude - Pipes and Cistern - Discussion

45 min are calculated as 3/4*60 = 3*15 = 45 min.

i:e 3/4 of 60 min(1 hr).

The first tank will take 3hrs to fill in half of the tank.

4 tanks will take 6/4=1.5hrs to fill the full tank.
but as half of the tank is already filled, it will take 0.75hr=45mins for the rest half tank.

If 1 tap takes 6 hours --> 2 taps takes 6/2=3 (half time as fill faster).

If 2 taps takes 6/2=3 (half time)---4 taps takes 3/2=1.5 (i.e 1:30 min).

1:30 min= 60 min +30 min= 90 min.

90 min (time taken by 4 tapes to fill full tank).

But left is only half tank.

So 90/2 = 45 min.

Now total time = 3hour+45 min.

One tap can fill tank completely in 6 hr.

Actually, tap's 1 hr work = 1/6.

--> Also, one tap can fill tank half in 3 hr.

--> When there are 3 more similar taps. Then total taps = 4.

4 tap's 1 hr work = 4/6.

Adding,

-->3/6 (since tap is filled half i.e. for 3 hrs by 1st tap) + x*4/6 = 1.

--> x because remaining x hr will be taken by 4 tap's to fill other half tank. Not necessarily 3 hr. That was taken by 1st tap alone.

On solving.

-->x = 3/4.

Getting total time = 3 hrs (tank filled half by 1st tap) + x.

--> 3+3/4.
-->15/4.
-->3:45 min.

2/3:1/2::1:x.

X = (1/2*1*3/2) = 3/4.

I did not got these two steps shall you explain me please in this step what is X why we should take the ratio.

1. Time taken by a pipe to fill half the tank = 3 hrs.

2. So, time taken by 1st pipe along with 3 other similar pipes (i.e 4 pipes).

= 3 hrs/4.

= 180 min/4.

= 45 min.

Adding 1 and 2,

Total time taken = 3hr 45 min.

Thanks @Vicky. That was clear and simple.

Thanks @Vicky.

1 pipe takes 6 hrs to fill the tank.
So 1 pipe take 3 hrs to fill half the tank.
Other half is filled with 4 pipes,
The part of the tank filled with 4 pipes in 1 hr = 4 * 1/6 = 2/3.

So, the time taken to fill half the tank = (1/2) / (2/3)= (1/2) * (3/2) = 3/4 hrs= 45 minutes.
So the total time = 3hrs 45 minutes.

Its pretty much a simple logic.

Tone tap 6 hrs to fill.

So 3 hrs to half fill.

A = 1/6.

4 taps 4a =4 * (1/6).

=> 2/3.

Now x be the tank capacity.

X/2 has filled already.

So remaining x/2 in 2/3.

X = 4/3 45 minutes.

So, totally 3 hrs 45 mts.