Aptitude - Pipes and Cistern - Discussion

Discussion Forum : Pipes and Cistern - General Questions (Q.No. 10)
10.
Two pipes A and B can fill a tank in 15 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, pipe A is turned off. What is the total time required to fill the tank?
10 min. 20 sec.
11 min. 45 sec.
12 min. 30 sec.
14 min. 40 sec.
Answer: Option
Explanation:

Part filled in 4 minutes = 4 1 + 1 = 7 .
15 20 15

Remaining part = 1 - 7 = 8 .
15 15

Part filled by B in 1 minute = 1
20

1 : 8 :: 1 : x
20 15

x = 8 x 1 x 20 = 10 2 min = 10 min. 40 sec.
15 3

The tank will be full in (4 min. + 10 min. + 40 sec.) = 14 min. 40 sec.

Discussion:
37 comments Page 2 of 4.

Pavi said:   1 decade ago
Thank you sundar.

Sudan said:   1 decade ago
I am weak in Maths. Please can anyone help me how to convert 44/3 into 14(2/3) ?

Nikhil said:   1 decade ago
@Sudan.

Change fraction into mixed fraction.

Eg: 7/2 can be written in form on 3(1/2).

Divide numerator with denominator and whatever remainder you got write it in bracket.

Eg: a/b can be written as c(remainder/b).

Teju said:   1 decade ago
Can anybody explain 1/20:8/15::1:x?

Deepak verma said:   1 decade ago
Its so simple:
After 4 minute the a was turned off means till 4 minutes a and b work together.
So,
4(1/15+i/20) = 7/15.

Let total time take = x.

Than 4 minutes after a is turned off so,

7/15+(x-4)*i/20 = 1.

x = 14 min. 40sec.
(2)

Anuraag2201 said:   1 decade ago
For all those who do not have clue as to how to convert improper fractions to mixed fractions. :/.

Are you sure are ready for quants?

Arunkumar said:   1 decade ago
@All.

Better don't confuse with the complex solutions! as, the main part of the quantitative exam is to minimize time, all should look for a shortest solution, (as given by @Kalpana) but not merely a solution (with complex steps).

For any question, a diagrammatic representation should be drawn roughly, to get a quick solutions. Also, 'learn by solving' is the key to prepare any exam.

All the best!

Vikash patel said:   1 decade ago
Why x-4?

Ramees said:   10 years ago
Easy to convert 44/3 into 14(2/3).

Divide 44 into 3 we get remainder 2(i.e 14*3 = 42).

Then we can write 14 (remainder/3) that is 14(2/3).

Neha said:   9 years ago
How to change the fraction value into minutes?


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