Math
posted by Amber on .
If you deposit P dollars into a bank account paying an annual interest rate r, with n interest payments each year, the amount A you would have after t years is A=P(1+r/n)^nt. Kevin places $100 in a savings account earning 6% annual interest, compound quarterly. If Kevin adds no more money to his account, how long will it take his money to double?

P = Po(1+r)^n.
r = (6%/4)/100% = 0.015 = Quarterly %
rate expressed as a decimal.
n = 4comp/yr * t = 4t.
P = 100(1.015)^4t = 200
(1.015)^4t = 200/100 = 2.00
4t*Log1.015 = Log2
4t = Log2/Log1.015 = 46.556
t = 11.64 Yrs.