Please show your work with the formulas written out. Please answer as if you can not use a calculator, or only use a four function calculator (because that is how I have to learn it). Do not just put down the calculator keystrokes I need to see every step and number to learn how to do it.

18. If your mutual fund has produced annual returns of 10%, -5%, 20% and 15%, what is your arithmetic average return? 19. What is the geometric average return of the returns in Problem #18? 20. What is the standard deviation of the returns in #18?