An investor purchases 100 shares of a $60 stock when the initial margin requirement is 50 percent and the maintenance margin is 30 percent.

(a) How much must the investor put up initially in order to purchase the stock?

(b) Calculate the actual margin if the price of the stock drops to $55.

(c) At what stock price will a margin call occur?

(d) If the stock price falls to $58, is the account restricted?