The future value of an investment $4\mathrm{.}1$ years from now, is $$1000.$ What is the interest rate $($expressed as an effective semi$-$annual rate$)$ if the PV today is $$742\mathrm{.}7.($Please use percents as your answer, so for example if your answer is $5\mathrm{.}23\%,$ write $"5\mathrm{.}23").$