The following bid and ask price and option prices were observed for a stock on May 14 of a particular year. Unless otherwise indicated, ignore dividends on the stock. The stock is priced at 161. The expirations are June 18, and July 16.

1- Using the information in the following table compute the risk-free rate

Maturity	Bid	Ask
06/17	5.95	5.85
07/16	6.1	5.95

Exercise Price	Call Price June	Call Price July	Put Price June	Put Price July
160	10.5	15	10.5	14
165	8.5	12	13.5	17

Examine the following pairs of calls, which differ only by exercise price. Determine whether either of them violates the rules regarding relationships between American options that differ only by exercise price.

a. June 160 and 165

b. July 160 and 165