An engineer has been offered an investment opportunity that will require an immediate cash outlay of $40,000 for a cash inflow of $3500 for each year of investment. However, she must state now the number of years she plans to retain the investment. Additionally, if the investment is retained for 6 years, a lump-sum amount of $37,000 will be returned to her; after 10 years, the lump-sum return is anticipated to be $53,500, and after 15 years, it is estimated to be $60,000. Money is currently worth 10% per year. Determine the present worth values for 6 years, 10 years, and 15 years, and decide if the decision is sensitive to the retention period