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.
Xx1884 said:
5 years ago
A-12,B-15,C-20 TOTAAL FACTOR IS 60,
A+B+C 1 HOUR WORK IS 5,
SO B one hour work is 15/5=3, C=20/5=4.
Here one thing mentioned A is working all time so we do not take that value so A+B =4+3=7 HOURS.
A+B+C 1 HOUR WORK IS 5,
SO B one hour work is 15/5=3, C=20/5=4.
Here one thing mentioned A is working all time so we do not take that value so A+B =4+3=7 HOURS.
(3)
Mahedi Bipul said:
5 years ago
According to me, the solution is
A * full time work + B * half time work + C * half time work = full part work.
=> (1/12) * x + (1/15) * (x/2) + (1/20) * (x/2) = 1.
x = (120/17) = 7.06
A * full time work + B * half time work + C * half time work = full part work.
=> (1/12) * x + (1/15) * (x/2) + (1/20) * (x/2) = 1.
x = (120/17) = 7.06
(15)
Kanaka said:
1 decade ago
Is this correct?
A is open all the time Part filled x/12.
B is open for 1 hr = 1/15.
C is open for 1 hr = 1/20.
x/12+ 1/15+ 1/20 = 1.
(5x+4+3)/60 = 1.
x = 60-7)/5 = 53/5 ~~ 5 hrs.
A is open all the time Part filled x/12.
B is open for 1 hr = 1/15.
C is open for 1 hr = 1/20.
x/12+ 1/15+ 1/20 = 1.
(5x+4+3)/60 = 1.
x = 60-7)/5 = 53/5 ~~ 5 hrs.
Narendra said:
10 years ago
Let's assume B works for x hours and C for y hours. So A will be working for x+y hours.
= (x+y)/12 + x/15 + y/20 = 1 (tank having 1 part).
= 9x + 8y = 60.
x = 4; y = 3.
= (x+y)/12 + x/15 + y/20 = 1 (tank having 1 part).
= 9x + 8y = 60.
x = 4; y = 3.
Potato singh said:
1 decade ago
Yes, take a bucket of 60 ltr capacity. Install 3 taps in your bathroom and get started.
Chandu said:
1 decade ago
why 2 hours are taken first and then 6...what purpose they are using please explain....
Sudheer said:
1 decade ago
1st operation is repeated here and atlast we have to check the left period check it.
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.
Karan said:
1 decade ago
i can not understand this question.
how 3/20 part is filled by A and B in 1 hour?
how 3/20 part is filled by A and B in 1 hour?
Kasi said:
1 decade ago
Hrishi. Your method is trail and error method. How can we say 7 hours directly ?
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