Objects detected by radar are plotted in a coordinate plane where each unit represents 1 mile. The point $(0,0)$ represents the location of a shipyard. A cargo ship is traveling at a constant speed and in a constant direction parallel to the coastline. At 9 A. M., the radar shows the cargo ship at $(0,15)$ . At 10 A. M., the radar shows the cargo ship at $(16,15)$ . How far is the cargo ship from the shipyard at 4 P. M.?