Samantha currently has $250,000 in her retirement savings account and looks forward to retiring when the account balance is at least twice that amount. If the interest rate earned is 9% compounded monthly, how long will she have to wait to retire?

Select one:

a. 7.8 years

b. 9.4 years

c. 15.2 years

d. 12.1 years

e. cannot be determined from given information