What is the standard deviation of returns for Stock A? What is the standard deviation of returns for stock B?

Intro We know the following expected returns for stocks A and B, given different states of the economy: State (s) Probability E(rA,s) E(rB,s) Recession 0.3 -0.03 0.04 Normal 0.5 0.12 0.07 Expansion 0.2 0.2 0.11 Note: If you can, it is much faster to solve these problems in a spreadsheet. However, the answer cannot be had simply by using the built-in AVERAGE() or STDEV( functions. If you are somewhat familiar with Excel, you might look into the SUMPRODUCT() function which is widely used to calculate weighted sums