Aptitude - Pipes and Cistern - Discussion

Hi everyone.

One of the easiest way
Whole tank is filled in 6hour.
Half tank will be filled in 3hour.

But now half tank is remaining and there are a total of 4taps.
So convert 3hour to minutes =180minute.

Now just divide,
180/4 =45 minutes.

So total will be 3hour 45 minutes.

The tap can fill half the tank in 3 hours i.e, in 180 min,
Then 4 taps can fill half the tank in 180/4 = 45 min,
Total: 3 hours 45 min.

A tap can fill a tank in 6 hours.

So, 1/2 of the tank is filled in 3 hours.
Now part of the tank filled by 4 same types of taps in 1 hour is (4 x 1/6) = 2/3,
This means 2/3 part is filled by 4 taps in 1 hr,
So 1 part is filled in 3/2 hr,
So 1/2 part is filled in 3/2 x 1/2 = 3/4 hr = 45 min.

Hence total time taken is 3 hr 45 min.

Simple.

Tank takes to fill within 6 hours. So half of the tank we stop the waterfall. So half tank fills times 3 hours. So remaining half tank we use 4 pipes. Each pipes s similar so each pipe takes 3 hours to fill the tank. But here we open together all pipes.

The remaining 3 hours will be reduced by 4 pipes. 3 hours =180mins.
So we know 180/4 pipes = 45mins. So already half tank is filled.
Remaining the half tank has been filled withn 45 mins so, 3hours 45 mins is the answer.

NOTE:
1 tap takes 6hours....now by using four similar such taps it take 3/2 hours to fill the tank......
since all of them are capable of filling the tank in 6 hours)therefore they share time equally----6hours/4taps=3/2 hours )

now lets go to the solution:::

to fill half of the tank...only one tap is used...therefore it takes 3hours.
now 3 more similar taps are used...means now we are using 4 taps which are of same kind..
as explained above..
to fill the tank by the use of four taps----it takes 3/2 hours
now what we require is just to fill the half of the tank
it takes 3/4 hours i.e [3/2]/[1/2]=3/4
threfore we get---3+3/4 means 3 hours 45 min

Given A tap can fill a tank in 6 hours.

After half the tank is filled i.e. after 3 hrs.

three more similar taps are opened i.e.

no. of taps to fill remaining half tank = 4 taps

when 1 tap is used = (3 hrs/1 tap)

when 4 taps are used = (3 hrs/4 taps)=45min

total= 3hrs+45min

Good explanation, Thanks. @Vicky!

I think logic behind 2/3 :3::1:x is;

X is the time taken by 4 tap to fill remaining 1/2 in hours.
AND, 2/3 part of tank is filled in 1 hour.
So, (2/3)/(1/2) = 1hr/xhr
Which can b also written as
2/3 : 3 :: 1.

To verify put 45 in place of X and check if the ratio r equal or not(deal in minutes what I mean is that conversation 1hr into 60 minute.

So, 1/x becomes 60/45 that is 4/3. And also, 2/3 : 1/2 is 4/3.

Tank filled in 1hr =6units.
For half an hour =3units.
Remaining 3units.
Now 3 more taps.....+previous 1 tap =4taps.
Efficiency =3/4.
Total =3*3/4(60)=3hr 45min.

Simple (3hour/1pipe)+(3hour/4pipe).
(First hf tank)+(sec half tank) = 3(3/4) = in hours then = 3(3*60)/4 = 3hr 45min.