You started an investment account 10 years ago with $1600, and it now has grown to $7200. a. What annual rate of return have you earned (you have made no additional contributions to the account)? b. If the investment account earns 12% per year from now on, what will the account's value be ten years from now? %. a. The annual rate of return is (Round to two decimal places.) !. b. The account's value will be $ (Round to the nearest dollar.)