In order to pay for college, Brooke's parents invest $20,000 in a bond that pays 8% interest compound semiannually. How much money will be there in 18 years?

To get the ending amount we will be using the formula

X=P (1 + r/n) ^nt, where

x is the ending amount

P is the principal amount

r is the interest rate, in decimal form

n is the number of compoundings in one year, in this case n=2

t is the number of years

next is we substitute

x = $20,000 (1 + 0.08/2) ^2 (18)

x = $20,000 (1 + 0.04) ^36

x = $20,00 (1.04) ^36

x = $20,00 (4.10393255398)

x = $ 82,078.65