Answer:
f = 889 Hz
Explanation:
As we know that when observer and source move relative to each other
Then in that case the frequency heard by the observer is different from actual frequency
The changed in the frequency is given as
[tex]f = f_0(\frac{v}{v - v_s})[/tex]
now we know that
v = 343 m/s
[tex]v_s = 3.5 m/s[/tex]
[tex]f_0 = 880 Hz[/tex]
now we have
[tex]f = 880(\frac{343}{343 - 3.5})[/tex]
[tex]f = 889 Hz[/tex]