You paid cash for $1,600 worth of stock a year ago. Today the portfolio is worth $2,626. a. What rate of return did you earn on the investment? (Negative value should be indicated by a minus sign. Round your answer to 2 decimal places.) Rate of return 64.13 % b. Now suppose that you bought the same stock but bought it on margin. The initial margin requirement was 65%. Recalculate your rate of return, ignoring any interest due.