Question 1140176
How long does it take for $3800 to double if it is invested at 7% compounded continuously?  Round your answer to two decimal places, if necessary.
<pre>Formula for time (t) that it takes an amount (PV) to "balloon" to a specific amount (FV), when compounded continuously: {{{matrix(1,3, t, "=", ln (A/P)/r)}}} 
Since the investment will double the FV (A) and PV (P) are unnecessary, and so we use 2 for A, and 1 for P. 
And, with r being annual interest rate, and t being time, in years, we get: {{{highlight_green(matrix(1,8, t, "=", (ln (2/1))/.07, "====>", t, "=", 9.9, years))}}}