Consider a whole life annuity paying $10,000 at the beginning of each year to (r), z 20 assuming that they are alive. This annuity is combined with a death benefit of $b> 0 payed to (r) at the end of the year of death. Assume the discount interest rate d = 0.08 and determine the value of b that minimizes he variance of the present value random variable of the just-described combination of annuity and insurance.