[" A boat-man can row a boat to make it move with "],[" aspeed of "10km/hinstill" water.Riverflows steadly "],[" at the rate of "5km/h" ,and the width of the river "],[" is "2km" .If the boat man cross the river along the "],[" minimum distance of approach then time elapsed "],[" in rowing the boat will be: "],[[" (1) "(2sqrt(3))/(5)h," (2) "(2)/(5sqrt(3))h," (3) "(3sqrt(2))/(5)h," (4) "(5sqrt(2))/(3)h]]