Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2019/ii/paper-4/29k/c/solution

Let and use the discounted multipliers . Under , the number of up moves in the remaining periods has the binomial distribution . Since
the conditional expectation in part (b) becomes
For an undiscounted stock, replace by and discount the resulting payoff by the appropriate power of .

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