Question

Holly wants to save money for an emergency. Holly invests $500 in an account that pays an interest rate of 4%. How many years will it take for the account to reach 12,000? Round answer to nearest hundredth.

Answer 1

Interest= principle x rate x time (in years)
11,500=(500)(.04)t
11,500=20t
575=t
575 years

Answer 2

Or a neater solution is to use the formula locates here:
http://www.1728.org/compint2.htm

Years = {log(total) -log(Principal)} ÷ log(1 + rate)
Years = log (12,000) -log(500) ÷ log (1.04)
Years = (4.079181246 - 2.6989700043) ÷ 0.0170333393
Years = 1.3802112417 ÷ 0.0170333393
Years = 81.029985812

Here's a link to a calculator
http://www.1728.org/compint.htm
Enter the numbers and the answer is 81.03