Precalculus (6th Edition) Blitzer

$42411.5$ feet per minute
Since, $s= r \theta$ The linear speed for the tip of the propeller is given by: $2 \pi r \times 2250$ or, $2 \pi r \times 2250=6\pi \times 2250$ Thus, we have (in feet per minute) $=2250 \times 6 \times 3.142 =42411.5$ feet per minute