Casey invested $1,225 in a certain bond that pays 19% interest compounded annually. How long will it take for Brad's investment to triple? Explain.

6.3 years

Step-by-step explanation:

The growth factor each year is 1+19% = 1.19. You want to find the number of years (t) that result in a multiplier of 3 for the account value:

3 = 1.19^t

Taking logarithms, you get ...

log (3) = t·log (1.19)

log (3) / log (1.19) = t ≈ 6.32

It will take a little more than 6 years for Casey/Brad's investment to triple in value.