Suppose johnson & johnson and the walgreen company have the expected returns and volatilities shown below, with a correlation of 21.2 %21.2%. upper e left bracket upper r right brackete [r] sd left bracket upper r right bracketsd [r] johnson & johnson 7.7 %7.7% 16.8 %16.8% walgreen company 10.7 %10.7% 19.9 %19.9% for a portfolio that is equally invested in johnson & johnson's and walgreen's stock, calculate: a. the expected return. b. the volatility (standard deviation).