6. The purpose of this problem is to learn how to measure returns over time using excel and to illustrate the effects of portfolio formation. Data You will conduct analyses on Apple Inc., Microsoft Inc., and International Business Machines Corp. with their historical monthly data. First, you need their monthly return data. Visit http://fmance.yahoo.com. Enter \"Apple\" or its ticker symbol \"AAPL\" in the \"Get Quotes\" box. Then click on \"Historical Prices\" (underlined in the screen shot below)