Answer
$19.13$ feet per second
Work Step by Step
An $8$-person crew means $n=8$.
Substitute $8$ to $n$ to obtain:
$s=15.18\sqrt [9] n$
$s=15.18\sqrt [9] 8$
$s=15.18(1.25992105)$
$s=19.12560154$
$s\approx19.13$ feet per second
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