Chris borrows $4,000 at an 8% interest rate to purchase 300 shares of Apple Stock at $40 per share. Required: a. What is the margin when he first purchases the stock? b. What is the remaining margin if the share price falls to $30 per share by the end of the year? c. Is there a margin call if the maintenance margin requirement is 30% ? Yes No d. What is the rate of retun on his investment? (Neaative value should be indicated