Solve the Problem $P$ (In $W$ ) Generated by a Particular Windmill Is Given By

Solve the problem.
-The power $P$ (in $W$ ) generated by a particular windmill is given by $P=0.015 V^{3}$ where $V$ is the velocity of the wind (in $\mathrm{mph}$ ) . Find the instantaneous rate of change of power with respect to velocity when the velocity is $9.1 \mathrm{mph}$ .

A) $22.6 \mathrm{~W} / \mathrm{mph}$
B) $3.7 \mathrm{~W} / \mathrm{mph}$
C) $0.4 \mathrm{~W} / \mathrm{mph}$
D) $8.3 \mathrm{~W} / \mathrm{mph}$