$8\mathrm{.}9.$ A stormwater$-$management system is being designed for a $($design$)$

life of $10$ years, and a $($design$)$ runoff event is to be selected such that

there is only a $1\%$ chance that the system capacity will be exceeded

during the design life. $($a$)$ Determine the return period of the design

runoff event. $($b$)$ If the CDF of the peak runoff rate, $Q($in $m^{7}s),$ in any

runoff event is given by

$F(Q)=$exp$[-$exp$(-Q)]$

what is the design $Q?$