A boat is crossing a river with a speed vb = 8.3 m/s relative to the water. The river is flowing at a speed vr = 2 m/s and has a width W = 750 m. 1) How much time is required to cross the river? a. t = 93.1 s b. t = 90.36 s c. t = 87.85 s d. t = 119.05 s e. t = 72.82 s