The speed of a longitudinal wave in a metallic bar is $400 \mathrm{~m} / \mathrm{s}$. If the density and Young's modulus of the bar material are increased by $0.5 \%$ and $1 \%$, respectively then the speed of the wave is changed approximately to $\_\_\_\_$ $\mathrm{m} / \mathrm{s}$.
