The Velocity of a Particle (In $\mathrm{ft} / \mathrm{s}$ ) Is Given By

Multiple Choice

The velocity of a particle (in $\mathrm{ft} / \mathrm{s}$ ) is given by $\mathrm{v}=\mathrm{t}^{2}-9 \mathrm{t}+4$ , where $\mathrm{t}$ is the time (in seconds) for which it has traveled. Find the time at which the velocity is at a minimum.

A) $4.5 \mathrm{~s}$
B) $9 \mathrm{~s}$
C) $2 \mathrm{~s}$
D) $4 \mathrm{~s}$