Problem 12-12 Using the spreadsheet below and the fact that Cola Co. and Gas Co. have a correlation of 0.6083, calculate the volatility (standard deviation) ofa portfolio that is 55% invested in Cola Co. stock and 45% invested in Gas Co. stock. Calculate the volatility by: a. Using Eq. 12.4 b. Calculating the monthly retums ofthe pottolio and computing its volatility directly e. How do your results compare? Date Jan Feb Mar Apr 0.84 6.60 18.36 00% 1.86 7.40 Jun 1.22 6.04 13.61 3.51% 00% Oct 0.00 Dec Correlation Cola Co, holding Gas Co. holding 45 Average retum Volatility a. Using Eq, 12.4 Portfolio volatility b. Calculating the monthly retums of the ponfolio and computing its volatility directly Date Jan Feb Mar Jun Aug Oct Dec Average retum Volatility c. How do your results compare? Both (a) and (b) results ane