The below table shows the list of prices for puts expiring in 30 days (T = 1/12). Using the put option with a strike price of $236, estimate the level of the VIX index. K p 230 2.14 231 2.37 232 2.62 233 2.91 234 3.23 235 3.60 236 4.01 237 4.47 238 4.95 Other parameters you'll need: s0 = $234.35 r = 0.74% T = 1/12 years (required precision 0.01 +/- 0.01) black scholes equation.PNG As a reminder, the cumulative probability function is calculated in Excel as follows: N(d1) = NORM.S.DIST(d1,TRUE) N(d2) = NORM.S.DIST(d2,TRUE) If the above equations don't load for whatever reason, here are the text versions of the equations as a back-up: c = So*N(d1) - K*e^(-rT)*N(d2) p = K*e^(-rT)*N(-d2) - So*N(-d1) d1 = [ln(So/K) + (r + 0.5*(sigma^2))*T] / [sigma * sqrt(T)] d2 = d1 - sigma*sqrt(T) To validate your equations, you may use the following information to ensure you have it coded correctly: s0 = 22 k = 25 r = 0.1 sigma = 0.2 T = 0.75 d1 = -0.2184 d2 = -0.3916 c = 1.03446 p = 2.22805