Doppler Effect Questions

A whistle producing sound waves of frequencies $9500\text{Hz}$ and above is approaching a stationary person with speed $v\text{m/s}$. The velocity of sound in air is $300\text{m/s}$. If the person can hear frequencies up to a maximum of $10000\text{Hz}$, the maximum value of $v$ up to which he can hear the whistle is: