Standing waves are produced by the superposition of two waves $y_{1}=0.05 \sin (3 \pi t-2 x)$ and $y_{2}=0.05 \sin (3 \pi t+2 x)$
where $\mathrm{x}$ and $\mathrm{y}$ are in meters and $\mathrm{t}$ is in seconds.
The speed (in $\mathrm{ms}-1$ ) of each wave is $\ldots \ldots$
(A) $1.5$
(B) $3.0$
(C) $3 \pi / 2$
(D) $3 \pi$