This time, you are not given the stock tree and you are required to calculate the up and down ratios using Cox-Ross-Rubinstein's approach For those who are unaware, u and d can be calculated using Cox-Ross-Rubinstein's up and down ratios O* Initial Stock Price (S) Strike Price (K) Risk-free rate (r; p.a.) Volatility (sigma) Time to Maturity (t; years) Number of time periods (n) d = e 64 66 0.06 0.35 0.75 3 u= en First, calculate u and d u d 64