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?
20 hours
25 hours
35 hours
Cannot be determined
None of these
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 2 of 4.

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.

Rahul said:   9 years ago
Given: B = 2 times of A.
C = 2 times of B.

Assume A = 1, so B= 2(A)= 2 and C= 2(B)= 4.
Total = 1 + 2 + 4 =7.
Now multiply it 7*5.
Answer = 35.

Bappa said:   1 decade ago
Don't be confuse.

A x hours and B is twice fast it means is that B is faster than A.

So B is x /2. By this way B is twice faster than A.

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.
(18)

Vikram kumar said:   9 years ago
ABC-A -B-C
5-35
7-1-2-4

Because 7 * 5 = 35 means that 1 * 35 = 35 answer, if we want to find B means 2 * 35 = 70h.

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.

Naveencool said:   9 years ago
Take A as x = 1, B = 2, C = 4.

The total is 7, each contribution is in 5 hours. Then 7 * 5 = 35 hours.
(1)

Ramya said:   9 years ago
In some problem, they subtracted the values and here it is dividing. Can you please explain in detail?

Suganthi said:   1 decade ago
Please any one help me
B is twice as fast A means
A=X; B=2X isn't it
Then how B = X / 2 will come

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?


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