Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 14)
14.
Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in:
Answer: Option
Explanation:
| (A + B)'s 1 hour's work = |  |
1 | + | 1 |  |
= | 9 | = | 3 | . |
| 12 | 15 | 60 | 20 |
| (A + C)'s hour's work = | |
1 | + | 1 | |
= | 8 | = | 2 | . |
| 12 | 20 | 60 | 15 |
| Part filled in 2 hrs = | |
3 | + | 2 | |
= | 17 | . |
| 20 | 15 | 60 |
| Part filled in 6 hrs = | |
3 x | 17 | |
= | 17 | . |
| 60 | 20 |
| Remaining part = | |
1 - | 17 | |
= | 3 | . |
| 20 | 20 |
| Now, it is the turn of A and B and | 3 | part is filled by A and B in 1 hour. |
| 20 |
Total time taken to fill the tank = (6 + 1) hrs = 7 hrs.
Discussion:
52 comments Page 3 of 6.
Ronak said:
8 years ago
As First A and B was started then after B is turned off and C is started so, After 6 hours ((A+C)+(A+B)+(A+C)) 17/20th part of the tank is filled when c is turned off now.
As given A+B fill the 3/20'th part in 1 hour so total 6+1 hours is the time taken to fill the Cistern.
As given A+B fill the 3/20'th part in 1 hour so total 6+1 hours is the time taken to fill the Cistern.
Shipon said:
8 years ago
Thanks @Vino.
Lokesh said:
7 years ago
Thanks @Ravi.
Kumar Gourav said:
7 years ago
@All.
I believe its taken 6hrs straight after 2hrs because if all the three taps are kept open all the time, then it will take 5hrs to completely fill the tank. But, since in the question its given that B & C are opened alternatively every hour, that's why I guess it would take one hour more for the tank to be filled up.
I believe its taken 6hrs straight after 2hrs because if all the three taps are kept open all the time, then it will take 5hrs to completely fill the tank. But, since in the question its given that B & C are opened alternatively every hour, that's why I guess it would take one hour more for the tank to be filled up.
Vaibhav kulkarni said:
7 years ago
Guys,
If 2 hr = 17/60 part.
Then ?hr =1 unit.
Cross multiplication we get 7 hr.
If 2 hr = 17/60 part.
Then ?hr =1 unit.
Cross multiplication we get 7 hr.
Salman pasha said:
7 years ago
It is coming as 6 hours.
Divya said:
5 years ago
Thanks for describing the answer @Alvin.
Anil said:
1 decade ago
First two hours 17/60 part tank filled.
We are taking every two hour calculation so after 6 hour 17/20.
If you consider next two hours means it will become 17/15 means tank is overflowing.
So only after 6 hour we calculating remaining part that is (1-17/20) = 3/20.
Now its A and B turn to fill the tank. It fill 3/20 part in one hour. So totally (6+1) = 7 hours.
We are taking every two hour calculation so after 6 hour 17/20.
If you consider next two hours means it will become 17/15 means tank is overflowing.
So only after 6 hour we calculating remaining part that is (1-17/20) = 3/20.
Now its A and B turn to fill the tank. It fill 3/20 part in one hour. So totally (6+1) = 7 hours.
Supratim ghosh said:
1 decade ago
why write 6 hrs?
Sudheer said:
1 decade ago
1st operation is repeated here and atlast we have to check the left period check it.
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