Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 5)
5.
A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is:
Answer: Option
Explanation:
Suppose, first pipe alone takes x hours to fill the tank .
Then, second and third pipes will take (x -5) and (x - 9) hours respectively to fill the tank.
 |
1 | + | 1 | = | 1 |
| x | (x - 5) | (x - 9) |
 |
x - 5 + x | = | 1 |
| x(x - 5) | (x - 9) |
(2x - 5)(x - 9) = x(x - 5)
x2 - 18x + 45 = 0
(x - 15)(x - 3) = 0
x = 15. [neglecting x = 3]
Discussion:
68 comments Page 5 of 7.
Sachin said:
1 decade ago
How can a pipe fill in both 3 and 9 hours. Hows it possible?
Only one answer must be true?
which one how to get?
Only one answer must be true?
which one how to get?
(1)
Trinesh said:
6 years ago
Why it take x-5?
The second pipe fills the tank 5 hours faster than the first pipe so there will be X+5.
The second pipe fills the tank 5 hours faster than the first pipe so there will be X+5.
(4)
Lakshmichandra said:
10 years ago
Here why we can not consider x+5? I did not understand this problem can any please explain?
Hitesh said:
3 years ago
Here we got 2 answers.
3 and 15 but for 3 we will get y= -2 from y+5 =x,
So, x = 15.
3 and 15 but for 3 we will get y= -2 from y+5 =x,
So, x = 15.
(4)
SHUBHADIP DAS said:
5 years ago
In how much time 2nd and 3rd pipe together fo the work? Please explain the answer.
(2)
Sai said:
1 decade ago
Why we have taken 1/x, 1/x-5, 1/x-9. Please can any one say me the reason?
Minion said:
9 years ago
@Sameeera.
Your solution seems to be apt to this problem. Thank you.
Your solution seems to be apt to this problem. Thank you.
Monu dhaka said:
8 years ago
@Lavanya.
Answer is 10 minutes {(18/24)+(8/32)}=1.
18-8 = 10minutes.
Answer is 10 minutes {(18/24)+(8/32)}=1.
18-8 = 10minutes.
Swapnil said:
7 years ago
1/x + 1/ (x-5) = 1/(x-9).
Why 1/(x-9) equate with 1/x + 1/ (x-5)?
Why 1/(x-9) equate with 1/x + 1/ (x-5)?
Lakshmi said:
1 decade ago
Why neglecting 3 in the answer please can any one say?
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