6. 請分別指出軟體生命週期中，waterfall與prototype兩種方法論的理念為何? (10分) 另外，請指出三個較常見的資料庫管理系統及其分別是由那些公司所開發? (10分)

1.Labor(workers) Output(bikes) Total fixed costs(dollars) Total variable cost(dollars) Total cost(dollars)0 0 200 1 20 100 2 50 3 60 4 64 The table above gives costs at Jan's Bike Shop. Unfortunately, Jan's record keeping has been spotty. Each worker is paid $100 a day. Labor costs are the only variable costs of production. What is the total cost of producing 50 bikes?