An investor currently holds the following portfolio: Amount Invested 8,000 shares of Stock A $16,000 Beta = 1.3 15,000 shares of Stock B $48,000 Beta = 1.8 25,000 shares of Stock C $96,000 Beta = 2.2 The investor is worried that the beta of his portfolio is too high, so he wants to sell some stock C and add stock D, which has a beta of 1.0, to his portfolio. If the investor wants his portfolio to have a beta of 1.72, how much stock C must he replace with stock D?