Pipe A can empty a tank in 12 hrs and pipe B can empty it in 24 hrs. If both the pipes are opened to empty in the fully filled tank . In how many hours will it be emptied tank?
Choose the correct choice from the following:
A) 6
B) 7
C) 8
D) 9
E) 10
Part emptied A in 1 hr= (1/12)   Part emptied B in 1 hr= (1/24)   Part emptied by (A+B) together in 1 hr=(1/12)+(1/24)=1/8   So, The tank will be empty in 8 hrs   Answer : 8
<result>C</result>
Pipe A can empty a tank in 12 hrs and pipe B can empty it in 24 hrs. If both the pipes are opened to empty in the fully filled tank . In how many hours will it be emptied tank?