We denote the price of the call option with strike price K by C(K). For a certain stock, we consider call options prices for the same expiration. Suppose that C(50) = 9.95 and C(55) = 6.55. On the basis of the convexity of call option prices (rather than some other reason), what is the bound that you obtain for C(62.50) ? Make it clear whether this is an upper bound or a lower bound and express your answer as an inequality that C(62.50) must satisfy.