posted by kim..need help .
The frequency of an ambulance's siren is 700 Hz.
If a pedestrian on the side of the road hears the siren at 756 Hz, approximately how fast and in what direction is the ambulance moving?
a- There is not enough information
b- 25 km/h, away from the pedestrian
c- 90 km/h, towards the pedestrian
d- 90 km/h, away from the pedestrian
e- 25 km/h, towards the pedestrian