Answer
$17.71$ feet per second
Work Step by Step
A $4$-person crew means $n=4$.
Substitute $4$ to $n$ to obtain:
$s=15.18\sqrt[9] n$
$s=15.18\sqrt[9] 4$
$s=15.181(1665)$
$s=17.70791082$
$s\approx17.71$ feet per second
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