Cov = E[Ri - E(Ri)(Rj-E(Rj)] Variance (B) = E[(Rb-E(Rb)]2 The 2nd formula was used to find the standard deviation for stock B in a question. I am confused. So another formula for variance if SD is not already given is derived from Cov? -> Variance (B) = E[(Rb-E(Rb)]2 Can anyone comment and explain the link here? Thank you
The first formula is for the the covariance of two random variables.
The second is for the variance of a single random variable.
https://analystprep.com/cfa-level-1-exam/quantitative-methods/covariance-and-correlation-example/
You’re welcome.
Thank you Sir!