Aptitude - Pipes and Cistern - Discussion

Thanks @Faysal.

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.

Good explanation, Thanks. @Vicky!

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

Time taken by one tap to fill half of the tank = 3 hours.
Part filled by one tap in 1 hour = 1/6,
Part filled by 4 taps together in 1 hour = 4 × 1/6 = 2/3.

Total part filled by one tap + total part filled by 4 taps = 1.
(3)×(1/6) + (x)×(2/3) = 1.
[where x is the time taken by 4 taps to fill the tank].
Solving the equation we get, x = 3/4.
Now,
The Total time taken to fill the tank = 3 hours + 3/4 hours = 15/4 hours, which can also be written as 3(3/4) hours, which is 3 hours 45 minutes.
So, the correct option is (b) 3 hours 45 minutes.

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 and nice explanation @Vicky.

a, b, c, d = 6 hrs.
a=6 * 1/2 = 3 hrs.
then 3 hrs.= 180 minutes.
180/4 = 45 minutes.
3 hrs. 45 minutes.