The margin requirement on the S8P 500 futures contract is 8%, and the stock index is cumrently 1,600 . Each contract has a multiplier of 550. Required: a. How much margin must be put up for each contract sold? b. If the futures price falls by 18 to 1,584, what will happen to the margin account of an investor who holds one contract? (Input the amount as a positive value.) c-1. What will be the investor's percentage return based on the amount put up as margin? (Negative value should be indicated by a minus sign. Round your answer to 2 decimal places.) c-2. What would be the current cash balance in the margin account