- Lower-risk investments require a rate of return compared with higher-risk investments. . The payback period is expressed as Internal rate of return is expressed as a . The is computed by discounting the future net cash flows from the investment the project's required rate of return and then subtracting the initial amount invested. 0. The net present value decision rule requires that when an asset's expected cash flows are discounted at the quired rate and yield a positive net present value, the project should be