Problem: On the basis of a two-factor model, consider two securities with the following characteristics:
Characteristic             Security A      Security B
Factor 1 sensitivity         1.5                   .7
Factor 2 sensitivity         2.6                 1.3
Nonfactor risk               25.0              16.0
The standard deviations of factor 1 and factor 2 are 20% and 15%, respectively, and the factors have a covariance of 255. What are the standard deviations of securities A and B ? what is their covariance ?