STACEY is considering investing in two securities, A and B, and the relevant information is given below:

State of Economy	Probability	Return on Security A (%)	Return on Security B (%)
Bear	0.5	1	4.9
Bull	1-0.5	11	4.9

Suppose Emma borrowed from her friend 77 shares of security B, which is currently sold at $86, and sold all shares of the security. (She promised her friend she would pay her back in a year with the same number of shares of security B). Then she bought security A with the proceeds obtained in the sales of security B shares and the cash of $1,761 she owned.

Calculate the standard deviation of her portfolio. Report your answer in decimal form, rounded to 4 decimal points.