4. A manager must decide how many machines of a certain type to purchase. Each machine can process 100 customers per day. One machine will result in a fixed cost of $4000 per day, while two machines will result in a fixed cost of $7600 per day. Variable costs will be $40 per customer, and revenue will be $90 per customer. (5 points) a) Determine the break-even point for both the cases, i.e., with one machine and with two machines b) If estimated demand is 100 to 130 customers per day, how many machines should be purchased? Why?