<PRE><B>Question 1101681</B>
formula is f = p * (1+r)^n


f is the future value
p is the present value
r is the interest rate per time period
n is the number of time periods.


in your problem:


f = 13230
p = 12000
r = .05
n = what you want to find.


the formula becomes 13230 = 12000 * (1.05)^n


divide both sides of the equation by 12000 to get:
13230/12000 = 1.05^n
take the log of both sides of the equation to get:
log(13230/12000) = log(1.05^n)
since log(1.05^n) is equal to n * log(1.05), your equation becomes:
log(13230/12000) = n*log(1.05)
divide both sides of the equation by log(1.05) to get:
log(13230/12000) / log(1.05) = n
solve for n to get:
n = 2


the money will grow from 12000 to 13230 in 2 years at 5% interest per year.


12000 * 1.05^2 = 13230


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