Example 3: Given the sample of realized returns in Example 2, suppose that half of the value of an investor's portfolio is invested in bonds, a quarter in company A shares and a quarter in company B shares. Calculate the mean and standard deviation of this portfolio. (5.75%, 0.6935%) We have (w, 0.5, w=0.25, wa 0.25) bonds B Year 0.5(6.1) +0.25(4.2) +0.25(3.9)-5.075 6.575 6.25 6.2 4.875 5.525 27 2 3