The Excel file for these exercises (which can be found on the website accompanying this book) gives five years of monthly prices for two Vanguard funds—the Vanguard Index 500 Fund (VFINX) and the Vanguard High-

Yield Corporate Bond Fund (VWEHX). The first of these funds tracks the Standard & Poor’s 500, and VWEHX is a junk-bond fund. Compute the monthly returns and the frontier of combinations of these two funds.