Question: Pipe A can fill an empty tank in 6 h and pipe B in 8 h. If both the pipes are opened and after 2 h pipe A is closed, then how much time pipe B will take to fill the remaining tank?
Options:
A) $ 7\frac{1}{2}h $
B) $ 3\frac{1}{3}h $
C) $ 2\frac{2}{5}h $
D) $ 2\frac{1}{3}h $
Show Answer
Answer:
Correct Answer: B
Solution:
- A’s one hour’s work $ =\frac{1}{6} $
B’s one hour’s work $ =\frac{1}{8} $
$ (A+B)’s $ two hour’s work $ =2( \frac{1}{8}+\frac{1}{6} )=\frac{28}{48} $
$ \therefore $ Remaining work $ =1-\frac{28}{48}=\frac{20}{48} $
Time taken by pipe B to complete remaining work
$ =\frac{\frac{20}{48}}{\frac{1}{8}}=\frac{20}{48}\times 8=\frac{20}{6}=3\frac{1}{3}h $