The magnitdue of velcoity of water current in a river of width d varies across the river as $V=\frac{u_0^{2}y}{2d}$   and  $u_0$ is velcity of man in still water,   is perpeniducalr distancee from one of the bank

time taken  to reach opposite bank in shortest path is  $\frac{\pi d}{3u_0}$

time taken to reach opposite bank in shortest time is  $\frac{d}{u_0}$

time taken to reach opposite bank  in shortest time is  $\frac{\pi d}{u_0}$

time taken to reach opposite bank in shortest path is  $\frac{\pi d}{2u_0}$