3 Suppose a stock price is lognormal with volatility . Consider a derivative with maturity T and payoff f(s(T))=s3(T). (a) Whant is its value at time 0 ? (b) What is the Delta of the option considered in this Problem? (Hint: your task is to evaluate erTERN(sT3). Recall that under the risk-neutral probability distribution, sT is lognormal, and therefore sT3 is also lognormal. Use the fact that if Z is Gaussian with mean m and standard deviation s then E[eZ]=em+1s2