Robert invested $10,000 in a fund on January 1, 2019. On July 1, 2019 the balance in his fund was $11,000 at which point he deposited an additional $800 into his account. On October 1, 2019 the balance in his account was $12,200 and he at which point he withdrew $700. On January 1, 2020 Robert had $11,900 in his account. (8 points) a) Calculate the dollar weighted rate of return on the fund using the simple interest approximation for fractional periods but do not assume that deposits and withdrawals are uniform throughout the period. b) Calculate the time weighted rate of return on the fund