Aptitude - Pipes and Cistern - Discussion

Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and

  • Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
  • Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
  • Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
  • Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
  • Give answer(E) if the data in both Statements I and II together are necessary to answer the question.

2. 

How long will it take to empty the tank if both the inlet pipe A and the outlet pipe B are opened simultaneously?

I. 

A can fill the tank in 16 minutes.

 II. 

B can empty the full tank in 8 minutes.

[A]. I alone sufficient while II alone not sufficient to answer
[B]. II alone sufficient while I alone not sufficient to answer
[C]. Either I or II alone sufficient to answer
[D]. Both I and II are not sufficient to answer
[E]. Both I and II are necessary to answer

Answer: Option E

Explanation:

 I. A's 1 minute's filling work = 1
16

II. B's 1 minute's filling work = 1
8

(A + B)'s 1 minute's emptying work = 1 - 1 = 1
8 16 16

Tank will be emptied in 16 minutes.

Thus, both I and II are necessary to answer the question.

Correct answer is (E).


Abhishek said: (Nov 1, 2012)  
If initially Tank is empty, There is no need of A and B filling and emptying work. Since tank is empty; time taken is 0 hr.

Mskools said: (Aug 3, 2013)  
Here in the question he has to specify whether the is full or half-full or how much portion it was full. As it was not mentioned in the question the correct option for this is D.

Aayush said: (Dec 20, 2015)  
Yes exactly, without knowing the initial state of the tank, it is impossible to answer the question.

Chirag With Deven said: (Jan 3, 2016)  
Hello guys, tank will never ever be filled because outlet pipe is taking half the time of inlet pipe or numeric data statement is reciprocal of each other.

Pavan said: (Aug 31, 2018)  
Here the time taken for empty the tank is less hence the tank cannot be filled completely.

Naman Agarwal said: (Feb 15, 2020)  
The outflow rate will be dependent on the water pressure which depends on height in the tank. So it's impossible to calculate by the given data.

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