An ambulance emits a warning signal with a frequency of $600\,\text{Hz}$. The speed of sound is $330\,\text{m s}^{-1}$. The ambulance moves towards an observer at a steady velocity of $25\,\text{m s}^{-1}$. What total change in the observed frequency occurs from the moment when the ambulance is far behind the observer to the moment when it is far ahead of the observer?
- A$49\,\text{Hz}$
- B$84\,\text{Hz}$
- C$91\,\text{Hz}$
- D$98\,\text{Hz}$