The following table contains monthly returns for Cola Co$.$ and Gas Co$.$ for $2013($the returns are shown in decimal form, i$.$e$.,0\mathrm{.}035$ is $3\mathrm{.}5\%).$ Using this table and the fact that Cola Co$.$ and Gas Co$.$ have a correlation of $-0\mathrm{.}0969,$ calculate the volatility $($standard deviation$)$ of a portfolio that is $60\%$ invested in Cola Co$.$ stock and $40\%$ invested in Gas Co$.$ stock. Calculate the volatility by:

a$.$ Using the formula:

Var$(R_p)=w_1^{2}SD(R_1{)}^2+w_2^{2}SD(R_2{)}^2+2w_1{w}_2$Corr$(R_1,R_2)SD(R_1)SD(R_2)$

b$.$ Calculating the monthly returns of the portfolio and computing its volatility directly.

c$.$ How do your results compare?

a$.$ Using the formula:

Var$(R_p)=w_1^{2}SD(R_1{)}^2+w_2^{2}SD(R_2{)}^2+2w_1{w}_2$Corr$(R_1,R_2)SD(R_1)SD(R_2)$

The volatility $($standard deviation$)$ of the portfolio is $\%.($Round to two decimal places.$)$