Answer:
It will take 4.96 year or 5 year to double the investment @ 15% interest rate.
Explanation:
Suppose you invest = P = $1
Double Investment = $2
Interest rate = r = 15%
Us following formula to calulate the number of year to make the investment double
A = P x ( 1 + r )^n
$2 = $1 ( 1 + 0.15 )^n
$2 / $1 = ( 1.15 )^n
$2 = 1.15^n
log 2 = n log 1.15
n = log 2 / log 1.15
n = 4.96 years
It will take 4.96 year or 5 year to double the investment @ 15% interest rate.