Waves and Sound question bank (Physics)

Two tuning forks $A$ and $B$ are sounded together giving rise to 8 beats in 2 s. When fork $A$ is loaded with wax, the beat frequency is reduced to 4 beats in 2 s. If the original frequency of tuning fork $B$ is 380 Hz then original frequency of tuning fork $A$ is $\_\_\_\_$ Hz.

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 $\_\_\_\_$ $\mathrm{m} / \mathrm{s}$.