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Expert: Sherry Wallin - 8/13/2009


Question
How many years will it take to double your money if you deposit it into a fund paying 10% compounded monthly?

Answer
zarak~
    The amount A after t years due to a principal P invested at an annual interest rate r compounded n times per year is A = P(1+(r/n))^(nt)
Here your r = .1, nt = 12t, principal = P and double the amount = 2P = A. Plug them in and solve for t:
2P = P(1+(.1/12))^(12t)-> 2P/P =(1.0083')^12t I used 3' in place of 3 bar ->
(1.0083')^12t (2)(1^12) = (1.0083')^t
Take the ln of both sides getting: ln(2)^(1/12) = ln(1.0083')^t -. (1/12)ln(2) = t*ln(1.0083') ->  [ln(2)]/[1*ln(1.0083') = t.

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Sherry Wallin

Expertise

I can answer most questions up through Calculus and some in Number Theory and Abstract Algebra.

Experience

I have had my Bachelor's Degree since 1987 and have been a teacher since 1988. I earned my Masters Degree in Mathematics May 2010. I have been teaching at the same community college since 2002.

Education/Credentials
I have taught 12 years at the community college level, medical college, and technical college as well as a high school instructor and alternative education instructor and charter school instructor.

Awards and Honors
Master's GPA 3.56 Bachelor's GPA 3.34 Post grad work not degree related GPA 4.0

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