The correlation between xbox Corp.'s (Ticker: XBX) returns and Diamondback Energy, Inc.'s (Ticker: FANG) returns is 0.154118907. Xbox Corp. has a variance of returns of 4.5311749 while Diamondback Energy, Inc. has a variance of returns of 0.0282081. Xbox Corp. has an average return of 28.781035 percent while Diamondback Energy, Inc. has an average return of 1.190338 percent. Calculate the standard deviation of returns for a portfolio consisting of 58 percent Xbox Corp. stock and 42 percent Diamondback Energy, Inc. stock.