Question

A train blowing a whistle of frequency $320 Hz$ approaches an observer standing on the platform at a speed of $66 m / s$ .The frequency observed by the observer will be ____ Hz,
(Given speed of sound $=330 ms ^{-}$ 1)

Answer 1

The correct answer is 400

$f_{app}​=f \left(\frac{v}{v-v_s}\right)$
$=320(\frac{330}{330-66}​)$
$=400Hz$