A siren has a frequency of 740 Hz when it is at rest, whereas it has an apparent frequency of 830 Hz when it is moving toward a stationary observer.

A siren has a frequency of 740 Hz when it is at rest, whereas it has an apparent frequency of 830 Hz when it is moving toward a stationary observer. What is the speed of the siren in the latter case? (For the speed of sound please use 343 m/s.)