Problem: A pipeline for transporting oil will connect two points A and B that are 3 miles apart and on opposite banks of a straight river 1 mile wide. Part of the pipeline will run under water from A to a point C on the opposite bank, and then about ground from C to B. If the cost per mile of running the pipeline under water is four times the cost per mile of running it above the ground, find the location of C that will minimize the cost (disregard the slope of the river bed). Provide justifications and citations for your responses.