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 3 of 4.
Aparna said:
1 decade ago
1/x+2/x+4/x = 7/x how is it possible?
Why don't we take x+2x+4X?
Can anyone explain me please?
Why don't we take x+2x+4X?
Can anyone explain me please?
Richa said:
1 decade ago
If B is half time as fast than A. Then B=2X?
Jayasankar said:
1 decade ago
Given condition,
b = 2a.
c = 4a(c=2b=2*2a=4a).
and a+b+c = 1/5(for one hour).
==> a+2a+4a = 1/5.
==> a = 1/35 (one hour work).
Total = 35.
b = 2a.
c = 4a(c=2b=2*2a=4a).
and a+b+c = 1/5(for one hour).
==> a+2a+4a = 1/5.
==> a = 1/35 (one hour work).
Total = 35.
Vikash Kumar Das said:
1 decade ago
As per the question we can solve as:
c=2b;-------->1.
b=2a;-------->2.
Also a+b+c=1/5(work done in 1 hour by a,b,c)--------?3.
Now substitute the value of c=2b and b=2a in 3.
So eqn.3 becomes a+2a+2b = 1/5.
Again substitute b=2a in place of b.
So eqn becomes 3a+4a = 1/5.
So solving we get the value of a = 1/35.
So that is d work done in 1 hr.
So total work done = 35.
c=2b;-------->1.
b=2a;-------->2.
Also a+b+c=1/5(work done in 1 hour by a,b,c)--------?3.
Now substitute the value of c=2b and b=2a in 3.
So eqn.3 becomes a+2a+2b = 1/5.
Again substitute b=2a in place of b.
So eqn becomes 3a+4a = 1/5.
So solving we get the value of a = 1/35.
So that is d work done in 1 hr.
So total work done = 35.
Usha said:
1 decade ago
1/x+2/x+4/x = 7/x. How it will possible?
SABYASACHI said:
1 decade ago
@Abhishek. We are calculating per hour, that's why we are taking the reverse of (x, x/2, x/4)...
Abhishek said:
1 decade ago
Why summation is not in this form?
X+x/2+x/4 = 1/5.
X+x/2+x/4 = 1/5.
Harsh Londhe said:
1 decade ago
Try to understand question, question itself has answer.
Let A fill tank in x hrs.
Therefore tank filled in one hrs is 1/x.
And B pipe is twice than A means 2 (1/x).
C pipe is twice than B means 2 (2 (1/x) ) i.e 4/x.
1/x+2/x+4/x = 1/5.
7/x = 1/5.
x = 35 hrs.
Let A fill tank in x hrs.
Therefore tank filled in one hrs is 1/x.
And B pipe is twice than A means 2 (1/x).
C pipe is twice than B means 2 (2 (1/x) ) i.e 4/x.
1/x+2/x+4/x = 1/5.
7/x = 1/5.
x = 35 hrs.
Ajay said:
1 decade ago
The question is say that The pipe C is twice as fast as B and B is twice as fast as A i.e means A:B:C = x:2x:4x respectively then why you are take 1/x, 2/x, 4/x.
Nick said:
1 decade ago
Why summation is in the form of 1/x + 2/x + 4/x?
It should be x + x/2 + x/4 ?
Isn't it?
It should be x + x/2 + x/4 ?
Isn't it?
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