Susan Norman seeks your financial advice. She wants to know how long it will take her to become a millionaire. She tells you that she has ​$1 comma 330 today and wants to invest it in an aggressive stock portfolio. The historical return on this type of investment is 18 ​% per year. How long will she have to wait if the ​$1 comma 330 is the only amount she invests and she never withdraws from the market until she reaches her​ $1 million? ​ (Assume no taxes on the​ earnings.) What if the rate of return is only 14 ​% ​annually? What if the rate of return is only 10 ​% ​annually?