Suppose it costs Apple about (70:) = 400 000 + 160:: + 131]me2 dollars to make x 3208 iPhone 6 in an hour at Foxconn Technology Group. a) Find the average rate of change of C with respect to X when the level of production passes: i. from 10 000 to 10 005; ii. from 10 000 to 10 001. b) Find the marginal cost function and use it to estimate the speed at which the cost increases when x =10,000 (This speed is called instantaneous rate of change or that of marginal cost]. Compare this with the exact production cost of the 10,001st iPhone. c) Find the average cost function C and the average cost of producing the First 10,000 iPhones. d) Using your answers to parts {is} and (c), determine whether the average cost increases or decreases to a production level of 10000 iPhones