(1 point) (Exercise 7.27) You invest $3000 at time t=0 and an additional $4000 at time t=1/2. At time t=1/2 you have $3200 in your account and at time t=1 you have $7300 in your account. a) Find the dollar-weighted rate of return on this investment. Do not use the simple interest approximation for fractional periods. ANSWER = %. b) Find the time-weighted rate of return on this investment. ANSWER = %