During a nOrmal economy with a $74\%$ of probability the common stick of d&f oil is expected to teturn $13\mathrm{.}2\%.$ During a recession with a $15\%$ probability the stock return is $6\mathrm{.}7\%$ during a boom with $11\%$ probbailith the stock return is $24\mathrm{.}5\%$ what is the standard deviation on these returns