Suppose that the initial value of an unlevered portfolio of Treasury securities is $0.5 million and its duration is 8.5. Suppose further that the manager can borrow $1.5 million and invest it in the identical Treasury securities so that the levered portfolio has a value of $2 million with the same duration of 8.5. What will be the new duration of the unlevered portion of the portfolio? Hint: as the starting point, you can assume the interest rate is changing by 100 basis points and compute the dollar duration accordingly.