\textbf{194-} In a medium where the speed of sound propagation is $330\ \dfrac{\text{m}}{\text{s}}$, a sound source moves along a straight path at a speed of how many meters per second so that the wavelength of the sound wave in front of it is $\dfrac{5}{6}$ of the wavelength of the sound wave behind it?
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(1) $20$ \hfill (2) $22$ \hfill (3) $50$ \hfill (4) $33$
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