Two pipes A and B can fill an empty tank in 8 hours and 12 hours respectively. They are opened alternately for 1 hour each, starting with pipe A first. In how many hours will the empty tank be filled?
1
\(9\frac{1}{4}\)
2
9
3
\(9\frac{1}{3}\)
4
\(9\frac{1}{2}\)