a tree 3 ft tall grows 8% each year. How long will it take the tree to get 14 feet tall? round to the nearest year.
14=3 x 1.08^y divide both sides by 3
4 2/3 = 1.08^y take the logs of both sides
y=Log(4 2/3) / Log(1.08)
y=20 years.
For a natural growth such as trees the following is a little more accurate:
14=3. e^(.08t) divide both sides by 3
4 2/3=e^(.08t) take the natural log of both sides.
t=ln(4 2/3) / .08
t=19.25 or about 19 years.
