The ordering and transportation cost C for the c mponents used in manufacturing a product is c= 100(200/x^2+ x/x+30), x≥1 where C is measured in thousands of dollars and x is the order size in hundreds. Find the rate of change of C with respect to x when (a) x = 10, (b) x = 15, and (c) x = 20. What do these rates of change imply about increasing order size?