What is the standard deviation of a stock's returns from the following sample of returns? Year Return 2017 30% 2018 5% 2019 15% 2020 -30% 2021 25% O 56.74% O 45.39% 23.82% 34.74% O 21.03% Which of the following is an example of an independent source of risk to a business? O Fire O Recession O War Inflation O Higher interest rates A company can issue coupon bonds at par with a coupon rate of 8%, and its tax rate is 20%. This company also has a cost of preferred stock of 10% and a cost of equity of 15%. What is the after- tax cost of debt? O 8.8% O 11% 6.4% O 1.6% O 8%