$30$ measurements of a loop$-$based delay subroutine executing a $10$ s delay are taken. The sample standard deviation is calculated to be $0\mathrm{.}341$ and the sample mean $9\mathrm{.}988.$ At $95$ confidence, determine the upper bound on the percent error in calibration of the delay routine. Provide your answer with $2$ decimal places with the $\%$ sign $($e$.$g $2\mathrm{.}30\%).$