A simple formula can help you estimate the number of years required to double your money. It's called the Rule of 72. You simply divide 72 by the interest rate (without the percent sign). For example, with an interest rate of 4%, your money will double in 72/4, or 18 years. part 1
If I invest $1000 at 3% interest, how long will take for my money to double?
If I invest $1000 at 6% interest, how long will take for my money to double?
If I invest $1000 at 8% interest, how long will take for my money to double?
If I invest $1000 at 12% interest, how long will take for my money to double?

part 2
If $120 doubles in approximately 13 years, what is the interest rate?
If $120 doubles in approximately 19 years, what is the interest rate?
If $120 doubles in approximately 23 years, what is the interest rate?

the top is just an explanation of what to do I just need one answered from part 1 and part 2