The costs of mining and transporting coal are roughly independent of the heating value of the coal. consider: (1) that the coal in the ground is valued at 50 cents/(million kj), (2) that mining costs are 8 dollars/tonne, and (3) that transportation costs are 8 cents/(tonneꞏkm). if the price of other delivered coals is 160 cents/(million kj), find: (a) the radius from the mine, in kilometers, that a coal of 32,560 kj/kg can be delivered and sold for zero profit or loss; (b) the same radius for a coal with a heating value of 23,200 kj/kg; and (c) the minimum heating value (in kj/kg) of a coal that could be used locally (i. e., a mine mouth plant).