The expected return is 6, Calculate these. I am stuff using equation (probability) x (Actual-expected)^2

Economic Status Probability Rate of Return Weak Economy .15 -5% Static Economy .60 5% Strong Economy .25 15% Refer to Exhibit above. What is your standard deviation? 0.65% 1.45% b. 4.0% d. 6.25% e. 6.4%