A pipeline for transporting oil will connect two points A and B that are 3 miles apart on opposite banks of a straight river that is 1 mile wide. Part of the pipeline will run under the water from point A to a point C on the opposite bank, and then above ground from point C to point B.

If the costs per mile for running the pipeline under the water is 4 times the cost per mile of running it above ground, find the location of point C that will. minimize the total cost.