An investor puts some money into an accumulation account annually in arrears. The payments start from $500 in the first year and increase by $100 per year until the tenth year. Afterwards, for the next 10 years, the payments remain level at $1,500 per annum. Then the investor stops investing in the account. Suppose the annual force of interest is given as 8(t) = 0.08 0t7 8(t) = 0.06 7