The performance of the common stock of Apple Stores is highly dependent upon the state of the economy. In a boom economy, the stock is expected to return $23\mathrm{.}0\%$ in comparison to $11\mathrm{.}0\%$ in a normal economy andnegative $14\mathrm{.}0\%$ in a recessionary period. The probability of a recession is $18\%.$ There is a $23\%$ chance of a boom economy. The remainder of the time the economy will be at normal levels. What is the standard deviationof the returns on Apple stock?