The equation of a plane progressive wave is given by \( y = 5 \cos \pi \left( 200 t - \frac{x}{150} \right) \) where \( x \) and \( y \) are in \( \text{cm} \) and \( t \) is in second. The velocity of the wave is ______ \( \text{m}/\text{s} \).
\( 120 \)
\( 150 \)
\( 200 \)
\( 300 \)
