A boat going down stream crosses a float at a point A. 't_1'minutes later the boat reverses its direction and in the next 't_2'minutes it crosses the float at a distance L from the point A. The velocity of the river is

A boat going down stream crosses a float at a point A. 't_1'minutes la

1.	A boat going down stream crosses a float at a point A. 't_1'minutes later the boat reverses its direction and in the next 't_2'minutes it crosses the float at a distance L from the point A. The velocity of the river is
Answer» `2L//t_1` `L//(t_1 + 2t_2)` `2L//(2t_1 + t_2)` `L//2t_1` ANSWER :D