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 1 of 4.
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)
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)
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)
Nikhil said:
5 years ago
The pipe C is twice as fast as B.
Means ratio of C:B = 2:1.
B is twice as fast as A.
Means B:A = 2:1.
Combine ratio of A:B:C = 1:2:4.
NOW,
The tank is filled in 5 hours by A,B,C.
so the addition of ratio =7(total parts of the tank)
So, 7*5 =35 hours to fill.
Now we have to find A's time.
A's ratio is 1. So divide 35by 1 =35 is the answer.
Means ratio of C:B = 2:1.
B is twice as fast as A.
Means B:A = 2:1.
Combine ratio of A:B:C = 1:2:4.
NOW,
The tank is filled in 5 hours by A,B,C.
so the addition of ratio =7(total parts of the tank)
So, 7*5 =35 hours to fill.
Now we have to find A's time.
A's ratio is 1. So divide 35by 1 =35 is the answer.
(8)
Ritwik said:
6 years ago
B is twice as fast as A so if A=x, B=2x then how x/2?
(3)
Vineeth said:
7 years ago
Considering the value of A as X, B as 2X and C as 4X. Can anybody help me in solving this ?
(2)
Sagen said:
7 years ago
@Manikandan.
A+B+C together fill the tank in 5 hrs. In 1 hr they together fill ta tank par 1/5 of the tank.
A+B+C together fill the tank in 5 hrs. In 1 hr they together fill ta tank par 1/5 of the tank.
R. Gowtham Raj said:
7 years ago
Here, it should be x + x/2 + x/4.
Manikandan said:
8 years ago
Here how that 1/5 comes?
Bhagyasree said:
8 years ago
@Savitha.
We know that capability of A, B, C.
More capability takes less time to complete the work. it means that strengths is inversely proportional to time.
A + 2A + 4A inversely to x/5(x is some constant)
X = 5*7A .......35A.
35A part work done in......1 hour.
A's total work.................?
So, ? =35hrs.
We know that capability of A, B, C.
More capability takes less time to complete the work. it means that strengths is inversely proportional to time.
A + 2A + 4A inversely to x/5(x is some constant)
X = 5*7A .......35A.
35A part work done in......1 hour.
A's total work.................?
So, ? =35hrs.
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