Answer:
[tex]v_{s}[/tex]= 47.53 mph
Explanation:
by using Doppler Effect
the frequency f' is the observed frequency by the observer :
by using relations
[tex]f' =[\frac{v}{v-v_{s}}]\times f\\[/tex]
where v is speed of sound in medium and [tex]v_{s}[/tex] is speed of source ( ambulance)
on solving above equation we get
[tex]v_{s} = \frac{(f' -f)v}{f'}[/tex]
substitute the values we get
[tex]v_{s} = \frac{( 960 -900)(340)}{960}\\v_{s} = 47.53 mph[/tex]
