The margin requirement on the S&P 500 futures contract is 10%, and the stock index is currently 1,800. Each contract has a multiplier of $250.

a. How much margin must be put up for each contract sold?
b. If the futures price falls by 1% to 1,782, what will happen to the margin account of an investor who holds one contract?
c. What will be the investor’s percentage return based on the amount put up as margin?