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# Normal Distribution: Mitchell's Serve

APSTAT-BY6U1C

The distribution of the speed of Mitchell’s tennis serve is approximately normal with a mean of $105.9$ miles per hour and a standard deviation of $7.4$ miles per hour.

If Mitchell is asked to serve at $80$%, which expression represents the speed (in miles per hour) at the $80$th percentile of this distribution?

A

$-0.84(7.4)+105.9$

B

$-0.80(7.4)+105.9$

C

$0.20(7.4)+105.9$

D

$0.80(7.4)+105.9$

E

$0.84(7.4)+105.9$