Consider a portfolio of 1000 fully discrete whole life assurance policies with unit benefit to 1000 policyholders aged 30. Suppose mortality follows AM92 and the annual interest rate is i=4%. (a) Describe how to calculate the retrospective reserve per policy in force at time 5. Provide an intuitive interpretation for each component. (Hint: you can start with computing the expected accumulated reserve for the whole portfolio and then calculate the reserve per policy). (b) Calculate the prospective reserve at time 5 per policy in force. Compare this result with the retrospective reserve per policy in force at time 5 calculated in (a) and provide an intuitive explanation