You want to build a two asset portfolio including SPDRs and T-bills that has an expected return of 3.36%. A SPDR is a standard and Poor's Depositary Receipt. A SPDR is an exchange traded fund that is designed to generate the same return as the S&P 500 index. What is the portfolio weight on the SPDRs ? Assume that the return on the t-bills is 3.0% and the expected return on the S&P 500 is 9.0%