Aptitude - Pipes and Cistern - Discussion

Considering the LCM of the all the four taps ie 6.

Now considering the capacity of tank be 6 units.

For the 1st half,

As only 1 tap is working so it fills 6/6 units/hr = 1 unit /hr (part filled by tap 1/total capacity of the tank).

As only 1 tap is working for the 1st half I.e. For 3 units of tank (total capacity of tank/2).

Calculations:

1 unit filled in 1 hr.

3 units filled in 3 hrs.

In second half 4 taps of same type are used, therefore it fills 4/6*6 = 4 units/hr (part filled by 4 taps/total capacity of the tank).

Now left out 3 units are filled by the combination of 4 taps.

Calculation:

4 units filled in 1 hr.

3 units filled in 3/4 hrs = 45 mins.

Therefore total time taken = time taken by 1st tap + time taken by combination of 4 similar taps.

= 3 hrs + 3/4 hrs = 3 hrs 45 mins.

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

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.

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.

A pipe can fill the tank in 6 hours, so in 1 hour the pipe can fill 1/6 th part of the tank.

1 hour--------->1/6 part of tank.

3 hours--------->1/2 part of tank.

According to the data which had given in the question:The similar three more taps are opened so total number of taps are:4.

These four taps together in hour can fill (1/6+1/6+1/6+1/6=4/6=2/3) 2/3 part of the tank.

So, total time equals to 3.75 hours which is equals to 3 hours 45 minutes.

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.

1 tap has filled half of the tank in 3 hours and remained half of the tank have to be fill by 4 taps and we know that tank will take total 6 hours to fill. So, now remaining time is 3 hours that is 180 minutes and we have 4 taps so the solution is 180/4=45 min that is the tank taken total time is previous 3 hours that is filled by only 1 tap and by 4 taps is 45 mins.

So the total time is 3 hours and 45 mins.

Here, given problem is that,

First half of the tank is filled in 3hrs by using only 1 tap.
After that 3 more pipes are opened so, now total working pipes 4(they are similar means takes the same time to fill the tank).

The remaining we have 6 - 3 = 3hrs.
3hrs means = 3 * 60 = 180min
So, equally this time shared by 4 pipes 180/4 = 45 min.
So total time is 3hrs 45 min.

Guys, it is very easy.

A tap can fill a tank by 6 hrs. Then one tap is closed after 6 hrs which means 6/2=3 hrs.
Then 3 more taps are opened so now totally there are 4 taps are opened.
We are having remaining time will be 6-3 =3 hrs.
So find 3/4 you get 0. 75 hrs which means 45 mins.
So the Answer will be 3hrs 45 mins.
Hope it will help you.

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.