6.30 Johnny sold short a 10-year par value 8% semiannual coupon bond yielding 7% compounded semiannually at issue. The broker's initial margin requirement was 50% of the value of the short position. As predicted by Johnny, the prevailing market interest rate increased to 9% shortly after he sold short the bond. After 7 months, Johnny covered the short position by buying back the bond from the market. (a) Calculate the bond price when Johnny sold short the bond, and when he purchased the bond from the market. b) Assuming that the margin deposit earned no interest, calculate the rate of return resulting from the short sale