Concern the future of the US Social Security Trust Fund, out of which pensions are paid. Figure 5.61 shows the rates (billions of dollars per year) at   which income.

I(t), from  taxes and interest is projected to flow into the fund and at which expenditures, E(t), flow out of the fund. Figure 5.62 shows the value of the fund as a function of time.

(a) Write each of the following areas in Figure 5.61 from 2016 to 2020 as an integral and explain its significance for the fund.
(i) Under the income curve
(ii) Under the expenditure curve
(iii) Between the income and expenditure curves
(b) Use Figure 5.62 to estimate the area between the two curves from 2016 to 2020.

Transcribed Image Text:

bn $/yr 1375 1175 975 fot 775 2015 2017 2019 2021 Auf- Figure 5.61 E(1) I(1) 2021 2023 2023 2025 t(year)