Assume a project will result in benefits of $1 trillion in 500 years by avoiding an environmental disaster that otherwise would occur at that time.

a. Compute the present value of these benefits using a time-constant discount rate of 3.5.

b. Compute the present value of these benefits using the following time-declining  discount rate schedule: 3.5 percent, years 1-50; 2.5 percent, years, 51-100; 1.5   percent, years 101-200; 0.5 percent, years 201-300; and 0 percent thereafter.