Question

You are driving along the highway at 27.8 m/s. An emergency vehicle, driving directly toward you (head-on) at 33.3 m/s in the opposite lane, is blaring its siren. The siren's main tone has a frequency of 700 Hz when the emergency vehicle is at rest. What frequency do you hear from the siren? The speed of sound is 343 m/s.

Answer 1

Required formula is
f'=(v+v0)f/(v-vs)

Answer 2

Given
v=343m/s
v0=27.8m/s
vs=33.3m/s
f=700hz
f'=?