The common stock of Air Express had the following annual returns over the last four years. What is the standard deviation of these returns? Yr1=11.7% Yr2 = 8.8% Yr3 = 16.7% Yr4 = -7.9% 2.70% 9.23% o 7.33% 10.66% 113.67% The net book value of an asset will generally: O Remain constant over the life of the equipment. Increase over the taxable life of the asset. O Vary in response to changes in the market value. O Decrease at a constant rate when MACRS depreciation is used. O Decrease at a slower rate using straight-line depreciation vs. using MACRS