Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 7)
7.
A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?
Answer: Option
Explanation:
Suppose pipe A alone takes x hours to fill the tank.
| Then, pipes B and C will take | x | and | x | hours respectively to fill the tank. |
| 2 | 4 |
 |
1 | + | 2 | + | 4 | = | 1 |
| x | x | x | 5 |
 |
7 | = | 1 |
| x | 5 |
x = 35 hrs.
Discussion:
33 comments Page 4 of 4.
Trishali said:
5 years ago
Basically they have used the concept of speed is inversely proportional to time. The question talks about how fast the pipes can fill the tank. Given that ratio, we inverse it to find the time.
So, A takes x hrs, B will take X/2 hrs because it is twice as fast as A and C will take x/4 hrs.
Now summation of work done by each pipe in 1 hr = (1/x+2/x+3/x) =7/x=1/5;.
So, from here x=35.
So, A takes x hrs, B will take X/2 hrs because it is twice as fast as A and C will take x/4 hrs.
Now summation of work done by each pipe in 1 hr = (1/x+2/x+3/x) =7/x=1/5;.
So, from here x=35.
(2)
Subhasis Mishra said:
4 years ago
A's 1 hr work = x,
B's 1 hr work = 2x,
C's 1 hr work = 4x,
Then, x+2x+4x = 1/5.
So,x = 1/35.
A can fill the tank in 35 hours.
B's 1 hr work = 2x,
C's 1 hr work = 4x,
Then, x+2x+4x = 1/5.
So,x = 1/35.
A can fill the tank in 35 hours.
(18)
Rkay said:
2 years ago
R*T = w
(4+2+1) * 5 = w
7*5 = w
W = 35
An efficiency = 1
Time taken = 35/1 = 35.
(4+2+1) * 5 = w
7*5 = w
W = 35
An efficiency = 1
Time taken = 35/1 = 35.
(6)
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