The Rule of 70 applies in any growth rate application.

The Rule of 70 applies in any growth rate application. Let’s say you have $1000 in savings and you have three alternatives for investing these funds.
-A savings account earning 1% interest per year.
-A U.S. Treasury bond mutual fund earning 3% interest per year.
-A stock market mutual fund earning 8% interest per year.
-How long would it take to double your savings in each of these 3 accounts?