Kristen invests $5,745 in a bank. the bank pays 6.5% interest compounded monthly. how long must she leave the money in the bank for it to double? round to nearest tenth of a year.

To solve this we are going to use the compounded interest formula: 
where
is the final amount 
is the initial investment
is the interest rate in decimal form 
is the time in years 

We know that initial investment is $5,745, so . We also know that Kristen wants his investment to double, so . Now, to convert the interest rate to decimal form, we are going to divide the rate by 100%: . Since the interest is compounded monthly, it is compounded 12 times per year: therefore, . Now that we have all the information we need, lets replace the values in our formula and solve for :










We can conclude that she must leave the money for 10.7 years in the bank for it to double.