Question

A person in front of a mountain is beating a drum at the rate of 40 per minute and hears no distinct echo. If the person moves 90 m closer to the mountain, he has to beat the drum at 60 per minute to not hear any distinct echo. The speed of sound is 

 (A) 320 ms^–1 

(B) 340 ms^–1 

(C) 360 ms^–1 

(D) 380 ms^–1

Answer 1

Correct option (C) 360 ms^–1

Explanation: 

For not hearing echo time interval between the beats of drum must be equal to time of echo