The equation of wave is given by \( Y = 10^{-2} \sin 2\pi(160t - 0.5x + \pi/4) \) where \( x \) and \( Y \) are in \( \text{m} \) and \( t \) in \( \text{s} \). The speed of the wave is ______ \( \text{km h}^{-1} \).