How to find the weighted deviation squared for returns and show process

Covarianceisa statistical measure of thedegree to which two or more series move together . Weighted Weighted deviation deviation Return Return Probability x Probability x squared for squared for Return on A Return on B Return on A Return on8 5.00% 0.000506 0.002162 7.20% 0.000015 0.000101 1.50% 0.000454 0.006427 on B Probability 25% 60% 15% onA Good OK Bad 15% 10% 5% 20% 12% -10% 3.75% 6.00% 0.75% -10.70% J0.000972 50.008691:-me 10.50% 3.1225 standard deviation of A= 3.1225% Standard deviation of B: 9.3226% 1110.301 ^2x 0.031225] ^20.70] ^2x [0.093226] ^2)+2(0.3)(0.7)("O0027150"))