Answer:
= 784.30 Hz
Step-by-step explanation:
Using the formula;
f₀ =(v.fs)/(v-vp)
Where; f₀ is the observed frequency, v is the speed of sound in air, fs is the frequency of the source and vp is the speed of the person towards the whistle.
In this case;
Speed of sound in air = 343 m/s
Speed of the person towards the whistle = 15 m/s
Frequency of the source = 750 Hz
Therefore;
f₀ = (343 × 750)/ (343 -15)
= 784.30 Hz