Chapter 13A – Lecture Notes
13A-2
iii. Compound interest – the example continued
1. What if the $108 was left in the bank for a
second year? How much would the original $100
be worth at the end of the second year?
2. The equation needed to answer this question is as
shown, where:
a. F = the ending balance.
b. P = the amount invested now.
c. r = the rate of interest per period.
d. n = the number of periods.
3. Solving this equation, the answer is $116.64.
a. The interest that is paid in the second year
on the interest earned in the first year is
known as compound interest.
B. Computation of present value
i. An investment can be viewed in two ways – its
future value or its present value. In the example
just completed, the present value was known and
the future value was the unknown that we
computed. Let’s look at the opposite situation –
the future value is known and the present value is
the unknown that we must compute.
ii. Present value – an example
1. Assume a bond will pay $100 in two years. If an
investor can earn 12% on their investments, what
is the present value of the bond?
2. The equation needed to answer this question is as
shown, where:
a. F = the ending balance.
b. P = the amount invested now.