You$$ve observed the following returns on Pine Computer$$s stock over the past five years: $18$ percent, $3$ percent, $16$ percent, $11$ percent, and $10$ percent.

a$.$

What was the arithmetic average return on the company$$s stock over this five$-$year period? $10\mathrm{.}40\%$

b$-1.$ What was the variance of the company$$s returns over this period? $????$

b$-2.$ What was the standard deviation of the company$$s returns over this period?$8\mathrm{.}20\%$