How to solve this without excel?

The following table lists possible rates of return on Company A and B. State of the Economy Deep recession Mild recession Average Mild boom Strong boom Probability 0.05 0.25 0.35 0.20 0.15 Company A -20% 0 10 15 30 Company B -40% 10 0 25 30 (a) Based on the above data calculate by using the appropriate formulae i. the standard deviations of returns for Company A and B ii. the covariance of returns between Company A and B iii. the correlation between Company A and B