Answer the following questions only if you are sure of the answers

Question 24.6 Explain why under perfect competition the price charged to customers is equal to the marginal cost.A level assurance policy pays a lump sum of $50,000 immediately on the death of a life aged 50, provided that he survives to his 60th birthday, and that his death occurs before that of another life currently aged 55. Derive an expression in terms of assurance functions for the expected present value of this benefit, assuming that both lives are subject to the same mortality table. [4]