Question 419618
A = P(1 + r/n)^(nt)
where
A is amount after time t
P is initial amount
r is interest rate
n is times compounded
t is time
.
    how long does it take $50 to grow to $200 invested at 4% compounded monthly
.
A is 200
P is 50
r is .04
n is 12
t is what we're solving for
.
A = P(1 + r/n)^(nt)
{{{ 200 = 50(1 + .04/12)^(12t) }}}
{{{ 4 = (1 + .04/12)^(12t) }}}
{{{ 4 = (1.0033)^(12t) }}}
{{{ log(1.0033,4) = 12t }}}
{{{ log(4)/log(1.0033) = 12t }}}
{{{ log(4)/(12*log(1.0033)) = t }}}
{{{ t = 34.72 }}} years