Answer:
The frequency heard by the observer is 2760.73 hertz. Explanation:
Frequency of source, f = 2640 Hz
Velocity of source,
The speed of sound, v = 343 m/s
Let f' is the frequency heard by the observer. According to Doppler's effect, the frequency of the observer is given by :
(as the source is moving towards observer)
f' = 2760.73 Hz
So, the frequency heard by the observer is 2760.73 hertz. Hence, this is the required solution.