question_answer

Two taps A and B can fill a tank in 12 hours and 8 hours respectively. If they are opened on alternate hours and if pipe B is opened first then in how many hours tank will be full?

A) \[9\frac{3}{4}\] hours     

B)               \[9\frac{1}{2}\] hours    

C) \[10\frac{1}{4}\] hours                                      

D) 9 hours

E) None of these