3.6 Summary (EMCG8)

• Always keep the rate of interest per time unit and the time period in the same units.
• Simple interest: $A = P(1 + in)$
• Compound interest: $A = P(1 + i)^n$
• Simple depreciation: $A = P(1 - in)$
• Compound depreciation: $A = P(1 - i)^n$
• Nominal and effective annual interest rates: $1 + i = \left( 1 + \frac{i^{(m)}}{m} \right)^{m}$

• Future value of payments:

  $$F = \frac{x\left[(1 + i)^{n}-1\right]}{i}$$

  Payment amount:

  $$x = \frac{F \times i}{\left[(1 + i)^{n}-1\right]}$$

• Present value of a series of payments:

  $$P = \frac{x \left[1 - (1 + i)^{-n} \right]}{i}$$

  Payment amount:

  $$x = \frac{P \times i}{\left[1 - (1 + i)^{-n}\right]}$$