using python with if statements. If there is a way to do it without a while statement that would be awesome. Thank you

Some investment advisors say that it's reasonable to expect a 7%=0.07 return over the long term in the stock market. Assuming that you begin with $1000 and leave your money invested, find if the principal is tripled in 16 years. If not, when will it triple? Use the following formula for determining these amounts: a=p(1+r)n where - p is the original amount invested (i.e., the principal of $1000 ), - r is the annual rate of return (7\%), - n is the number of years (16) and - a is the amount on deposit at the end of the nth year