**Question 308** risk, standard deviation, variance, no explanation

A stock's standard deviation of returns is expected to be:

- 0.09 per
**month**for the first 5 months; - 0.14 per
**month**for the next 7 months.

What is the expected standard deviation of the stock per **year** ##(\sigma_\text{annual})##?

Assume that returns are independently and identically distributed (iid) and therefore have zero auto-correlation.