question_answer

Pipe A can fill a tank in 4 hours and pipe B can fill it in 6 hours. If they are opened at alternate hours and if pipe A is opened first, in how many hour will the tank be filled?

A)  5 hour                 

B)         \[5\frac{2}{3}\] hours

C)  4 hours         

D)         \[4\frac{2}{3}\]hours