he correct answer given is option 4th But my answer Please

Last updated: 6/11/2023

he correct answer given is option 4th But my answer Please explain the question and provide other solutio en the previous one 21 A person have a whistle emitting continuously a sound of frequency 660 Hz While producing this sound he is running towards a vertical wall with a speed of 5 m s If the speed of sound in air is 335 m s then number of beats heard by him will be 1 20 Hz 2 10 Hz 3 8 Hz 4 No beats will be heard