Find the time required for an investment of $4000 to grow to $7000 at an interest rate of 6.5% per year, compounded quarterly. (Round your answer to two decimal places.)

Since every year, an amount 'x' will become 'x*1.065', every quarter it will become x*(1.065)^(n/4) for any number of quarters 'n'. So 7000=4000*(1.065)^(n/4). Solve for n: 7/4=(1.065)^(n/4) ln(7/4)=(n/4)ln(1.065) 4*ln(7/4)/ln(1.065)=n n=35.54 quarters or 8 years, 10 months, 19 days.