A pipe can fill a tank in x hours and another pipe can empty it in y (y > x) hours. If both pipes are open, in how many hours will the tank is filled?

A. (x - y) hours

B. (y - x) hours

C. $$\frac{{xy}}{{x - y}}$$ hours

D. $$\frac{{xy}}{{y - x}}$$ hours

Answer: Option D

Solution(By Examveda Team)

Net part filled in 1 hour
$$\eqalign{ & {\text{= }}\left( {\frac{1}{x} - \frac{1}{y}} \right) \cr & = \left( {\frac{{y - x}}{{xy}}} \right) \cr} $$
∴ The tank will be filled in
 $$ = \left( {\frac{{xy}}{{y - x}}} \right)\,\,{\text{hours}}$$