A tank is fitted with two taps A and b: In how much time will the tank be full if both the taps are opened together?
I. A is 50% more efficient than B
II. A alone takes 16 hours to fill the tank
III. B alone takes 24 hours to fill the tank

Let total work to be done is 48 units

Case 1 : I and II

A takes 16 hours => B=24 hours  (since A is 50 percent more efficient than B)

A does 3 units/hour

B does 2 units/hour

Total per day work = 5 units

Total time taken = 48/5 hr

Case 2 : I and III

B takes 24 hours => A = 16 hours (since A is 50 percent more efficient than B)

Together they take = 48/5 hours

Case 3 : II and III 

B takes 24 hours

A takes 16 hours

Together they take = 48/5 hours