Hi, I hope that you can help me with this question. I am currently studying for my corporate finance exam. Thank you in advance!

You find a certain stock that had returns of 14 percent, 11 percent, 21 percent, and 22 percent for four of the last five years. The average return of the stock over this period was 12 percent.

What was the stock's return for the missing year and what is the standard deviation of the stock's returns??