please help with part 3!

We know the following expected returns for stocks A and B, given different states of the economy: Part 1 [. Attempt 1/10 for 1.5 What is the expected return farstock A ? Correct The expected return is the weighted average return across all states of the economy: E(rA)=(psE(rA,s)) What is the expected return for stock B? Correct E(rB)=s(psE(rB,s))=0.10.03+0.50.06+0.40.1=0.073 Part 3 What is the standard deviationgf returns for stock A