Using the uploaded Excel document with a $10\%$ discount rate already entered, calculate the NPV of a mobile unit by entering the investment costs $($a negative number$)$ under year $0($cell D$11)$ for the cost of leasing, then purchasing, and finally a joint venture to see the net present value over $10$ years $($cell e$15).$ Based on your entries and the net present value $($this needs to be a positive number$).$ Is it better to lease, purchase, or joint venture a radiology unit and why?