1. Present Values.

Compute the present value of a $100 cash flow for the following combinations of discount rates and times.
a. r = 8 percent. t = 10 years
b. r = 8 percent. t = 20 years
c. r = 4 percent. t = 10 years
d. r = 4 percent. t = 20 years

2. Future Values: Compute the future value of a $100 cash flow for the same combinations of rates and times as in problem 1.

To compute the present value of a cash flow, we use the formula:

PV = CF / (1 + r)^t

Where PV is the present value, CF is the cash flow, r is the discount rate, and t is the time period.

1. Present Values:

a. r = 8 percent, t = 10 years:
PV = 100 / (1 + 0.08)^10 = 46.61

b. r = 8 percent, t = 20 years:
PV = 100 / (1 + 0.08)^20 = 21.73

c. r = 4 percent, t = 10 years:
PV = 100 / (1 + 0.04)^10 = 67.56

d. r = 4 percent, t = 20 years:
PV = 100 / (1 + 0.04)^20 = 45.26

2. Future Values:

To compute the future value of a cash flow, we use the formula:

FV = CF * (1 + r)^t

a. r = 8 percent, t = 10 years:
FV = 100 * (1 + 0.08)^10 = 215.89

b. r = 8 percent, t = 20 years:
FV = 100 * (1 + 0.08)^20 = 466.10

c. r = 4 percent, t = 10 years:
FV = 100 * (1 + 0.04)^10 = 148.02

d. r = 4 percent, t = 20 years:
FV = 100 * (1 + 0.04)^20 = 219.11

By plugging in the given values into the respective formulas, you can easily calculate the present and future values of the given cash flows.