The Running$-$based Anaerobic Sprint Test $($RAST$)$ calculates power over a series of $6$ x $35$ m sprints. Calculate Matt$$s Fatigue Index $($FI$)$ if he weighs $187$ lbs$.(85$ kg$)$ using the following data:

Rep $1=4\mathrm{.}56$ sec $($fastest$)$ and Rep $6=5\mathrm{.}99$ sec $($slowest$).$

Total time for all $6$ sprints $=33\mathrm{.}75$ sec$.$