John, an investment adviser, tells Lisa that if she's willing to invest the amount of $$100$ today, he can increase this investment by $3$ times in $7$ years. What annual rate of return is John promising on this investment?

r $=$

$\%$

INSTRUCTIONS: Place your answer in PERCENTAGE form with at least $2$ decimal places. For example, an answer of three and one$-$quarter percent is entered as $3\mathrm{.}25$ and not as $0\mathrm{.}0325.$ ALSO, DO NOT USE A PERCENT SIGN IN YOUR ANSWER. You should work your analysis using at least four decimal places of accuracy.