Use the following information for questions 21.18 and 21.19: The current price of a stock is 10 and it is expected to increase or decrease in price by 10% over each of the next two 6-month periods. The annual risk-free rate with continuous compounding is 6%. The stock pays no dividends. 21.18. (CAS8-S02:27a] Determine the value of an American put option with a strike price of 10.50 maturing in one year. 21.19. (CAS8-S02:27b] Determine the number of shares of stock and the amount of bonds earning the risk-free rate to be held at T = 0 in the replicating portfolio for the put option