In Yahoo Finance, find the weekly prices from 09/01/2017 to 08/31/2020 for two Vanguard funds the Vanguard Index 500 fund (symbol VFINX) and the Vanguard High-Yield Corporate Bond fund (VWEHX). The first of these funds tracks the Standard and Poors 500, and VWEHX is a junk-bond fund. Compute the weekly mean returns, sample variance, sample standard deviation, sample covariance, and correlation statistics. Graph a weekly mean return and standard deviation frontier of the portfolios composed of these two funds.