You find a certain stock that had returns of $9\mathrm{.}9\%,16\mathrm{.}9\%,21\mathrm{.}9\%,$ and $17\mathrm{.}9\%$ for four of the last five years. The average return of the stock over this period was $11\mathrm{.}2\%.$ Assume the face value of the bond is $$1,000.$

What was the stock$$s return for the missing year?

What is the standard deviation of the stock$$s return?