4. You will need to replace your quadcopter manufacturing system in seven years. You estimate the replacement cost at that time will be $950,000. If you can sell quadcopters for $550 each and they cost $250 each to manufacture and sell, how many quadcopters do you need to sell each year to pay for the replacement system? Your MARR is 5%. Select one: a. 389 b. 452 c. 212 d. 537 e. 622