A Put-Option Valuation
Suppose the value of an asset today is $50, and it is known that in one year the asset price will go up by u = 1.2 or down by d = 0.8 (i.e., uS = $60 and dS = $40, respectively). What is the value of a European put option with an exercise price of $55 that expires in T = 1 year? Assume a risk-free rate of 6% compounded continuously.