SOLUTION: Word Problem: An initial deposite of $4000 is made in a savings account for which the interest is compounded continuously. The balance will triple in 15 years. What is the ann

Question 5842: Word Problem:
An initial deposite of $4000 is made in a savings account for which the interest is compounded continuously. The balance will triple in 15 years. What is the annual rate of interest for this account?
I took the A=Pe to the rt formula.
12000=4000e to the 15r
divided 4000 to each side
3=e to the 15 r
then I found the natural log of both sides
ln3=ln15 to the r
I divided by ln15
ln3/1n15=r
Is this right?
Answer by Abbey(339) (Show Source): You can put this solution on YOUR website!
You made a mistake when you took the ln of both sides:
It should have read:

and because the lne = 1:

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