3. (Sigma estimation) Traders in major financial institutions use the Black-Scholes formula in a backward fashion to infer other traders' estimates of o from option prices In fact, traders frequently quote sigmas to each other, rather than prices, to arrange trades. Suppose a call option on a stock that pays no dividend for 6 months has a strike price of $35, a premium of $2.15, and time to maturity of 7 weeks The current short-term T-bill rate is 7%, and the price of the underlying stock is $36 12 What is the implied volatility of the underlying security?