Question

Suppose that any given year, the value of a certain investment is increased by 15%. If the value is now $15,000, in how many years will the value be $21,000?

Answer 1

use logarithms

Answer 2

Anything and everything can be solved using logarithms

Answer 3

\[21000 = 15000(1.15)^t\]

Answer 4

And you can simplify that to be 1.4 = (1.15)^t....right?

Answer 5

yes

Answer 6

solve for t

Answer 7

Then take the log of both sides and solve for t

Answer 8

\[1.4=(1.15)^t\]
\[t=\frac{\ln(1.4)}{\ln(1.15)}\] in english "the log of the total divided by the log of the base"