In the gear train shown, gear $3$ is carried on arm $5$. Gear $3$ meshes with gear $2$ and gear $4$. The number of teeth on gear $2$, $3$, and $4$ are $60$, $20$, and $100$, respectively. If gear $2$ is fixed and gear $4$ rotates with an angular velocity of $100$ $rpm$ in the counterclockwise direction, the angular speed of arm $5$ (in $rpm$) is
- $166.7$ counterclockwise
- $166.7$ clockwise
- $62.5$ counterclockwise
- $62.5$ clockwise