You receive a $4,000 check from your grandparents for graduation. You decide to save it toward a down payment on a house. You invest it earning 9% per year and you think you will need to have $8,000 saved for the down payment. How long will it be before the $4,000 has grown to $8,000? To double the money you received from your grandparents, it will take years. (Round to one decimal place.)