The back wall of an auditorium is 30.0 m from the stage. If you are seated in the middle row, how much time elapses between a sound from the stage reaching your ear directly and the same sound reaching your ear after reflecting from the back wall?

0.0875 sec

Explanation:

Using the relationship to calculate the time that elapse 2x = vt

x = distance between the source and the reflector

v is the velocity of sound in air

t = time elapsed

Given x = 30.0m and v = 343m/s

substituting the values into the formula above to get the total time elapsed t;

t = 2x/v

t = 2 (30) / 343

t = 60/343

t = 0.175sec

If you are seated in the middle row, the time that will elapse between the sound from the stage reaching your ear directly will be;

0.175/2 = 0.0875 secs