4. COMPARING TECHNOLOGIES Suppose a factory can produce a given output level using four different combinations of inputs (A,B,C,D). Assume per-unit prices of labor, capital, and natural resources are PL = $10, PK = $30, and PN = $50. Units of Units of Units of Natural Total Cost Labor, L Ca nital, K Resources, N Technology a) Calculate the total production cost of each technology. In the long run, when all inputs are variable, what is the most costefficient technology? b) In the short run, when the factory's natural resources input is xed at N = 4 (no more, no less), what is the minimum cost (or \"economically efficient\") technology? NOTE: A fixed input is not variable (can't choose its level), so if you don't have enough of that input, you may not be able to use some technologies. c) Alternatively, in the short run, when the factory has signed a contract promising to hire no more than 3 units of capital (\"robots\"), and the price of capital has fallen to PK = $10 what is the best technology