Pipe A can fill a tank in 10 hrs and pipe B can fill it in 8 hrs. If both the pipes are opened in the empty tank.There is an outlet pipe in 3/4 th of the tank. In how many hours will it be fill 3/4th of that tank?  Choices.
A) 3 hr B) 3.10hr C) 3.15 hr D) 3.20 hr E) 3.30 hr
Part filled A in 1 hr= (1/10)   Part filled B in 1 hr= (1/8)   Part filled by (A+B) together in 1 hr=(1/10)+(1/8)=18/80   So, The tank will be full in 80/18 hrs.   Time taken to fill Exact 3/4th of the tank = (80/18) *(3/4) = 3.20 hrs   Answer : 3.20 hr
<result>D</result>
Pipe A can fill a tank in 10 hrs and pipe B can fill it in 8 hrs. If both the pipes are opened in the empty tank.There is an outlet pipe in 3/4 th of the tank. In how many hours will it be fill 3/4th of that tank?