Question 1125107
the formula for simple interest is i = n * p * r


i is the interest
n is the number of time periods
p is the principal
r is the interest rate per time period.


when the investment is doubled, the interest is equal to the principal.


the formula becomes p = n * p * r


divide both sides of this equation by po to get 1 = n * r


divide both sides of this equation by r to get 1 / r = n


since r = .12, the formula becomes 1 / .12 = n which results in n = 8 and 1/3 years.


that's how long it will take for the money to double.


the total future value of the investment is given by the formula f = p + i.


when i = p, the formula becomes f = p + p which results in f = 2 * p, meaning the money has doubled.


so the minimum number of years for the money to double would be 8 and 1/3 years.