You've observed the following returns on SkyNet Data Corporation's stock over the past five years: 15 percent, -15 percent, 17 percent, 27 percent, and 10 percent.

a.What was the arithmetic average return on the company's stock over this five-year period?

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?

For a I got 10.8% which is right

for b I got 0.01970 and I'm not sure why this is incorrect

for b-2 i got 14.03% and I'm not sure why this is incorrect