A man in a boat is 3 km offshore and wishes to go to a point on the shore that is 5km from the point that is directly opposite his present position. The man can walk at 4 km/h and row at 2 km/h. At what point should he land so as to reach his destination in the shortest time? What is the traveling time?
I set up the equation as follow
Differentiating and found a local minimum at
However, the answer in supposedly 3.27 km, 2.55 hours.
What am I doing wrong?