What is the standard deviation of Stock A returns given the information below about its returns across future states of nature?

What is the standard deviation of Stock B returns given the information below about its returns across future states of nature?

Prob Stock A State Dep Rec Norm Boom Return 0.1 -0.25 0.3 0.12 0.4 0.33 0.2 0.42 Prob Stock B State Dep Rec Norm Boom Return 0.1 0.04 0.3 0.18 0.4 -0.12 0.2 0.08