6. Redo your analysis to allow for short sales by removing the constraint that each portfolio weight is greater than or equal to zero . Use Solver to calculate the ( annual ) portfolio standard deviation for the minimum variance portfolio , and when the annular portfolio return are set to 5% , 10% , 20% , 30 % , and 10 % . Plot the unconstrained efficient frontier on an XY Scatter Plot . How does allowing short sales affect the frontier ?"