# Moderate Time and Work Solved QuestionAptitude Discussion

 Q. Pipes $A$ and $B$ can fill a tank in 12 min and 16 min respectively. Both are kept open for '$n$' min and then $B$ is closed and $A$ fills the rest of the tank in 5 min. The time '$n$' after which $B$ was closed is:
 ✖ A. 3 min ✖ B. 2 min ✖ C. 5 min ✔ D. 4 min

Solution:
Option(D) is correct

$n\left(\dfrac{1}{12}+\dfrac{1}{16}\right)=\dfrac{28n}{192}$

$\Rightarrow$ Left capacity = $1-\dfrac{28n}{192}$

This is filled by $A$ in 5 min and fills $\dfrac{1}{12}$ in 1 min

$\Rightarrow \dfrac{192-28x}{192}=\dfrac{5}{12}$

$n$= 4 min

## (1) Comment(s)

Vaibhav Gupta
()

Alternative:

Clearly,

n+5/12+n/16=1

Solving it we get n=4