A whistle producing sound waves of frequencies 9500 Hz and above is approaching a stationary person with speed $v$ ms$^{-1}$. The velocity of sound in air is $300$ ms$^{-1}$. If the person can hear frequencies upto a maximum of $10{,}000$ Hz, the maximum value of $v$ upto which he can hear the whistle is\\
(1) $30$ ms$^{-1}$\\
(2) $15\sqrt{2}$ ms$^{-1}$\\
(3) $15/\sqrt{2}$ ms$^{-1}$\\
(4) $15$ ms$^{-1}$