Turn to the Mini$-$S&P $500$ contract in Figure $22\mathrm{.}1.$ If the margin requirement is $10\%$ of the futures price times the contract multiplier of $$50,$ a$)$ how much must you deposit with your broker to trade the December maturity contract?

$$b$)$ If the December futures price increases to $4,400,$ what percentage return will you earn on your investment if you entered the long side of the contract at the price shown in the figure?

$$c$)$ If the December futures price falls by $1\%,$ what is your percentage return?