The current price of a stock is $55. Calculate the value of an American put option on the stock using a two-step binomial tree given the following information. The strike price of the option, K = $57, each time step is one year, the risk-free interest rate, r = 5%, u =1.25, d = 0.8, and p = 0.628

Part 2.

Given that u= e^(σ√∆T), calculate the implied volatility for the American put option in Part 1.

So=55