The speed of sound at sea level is normally about 340 m/s. A car honks itshorn as it drives toward an observer. The frequency of the horn is 800 Hz, but theobserver hears an 860-Hz pitch. What is the velocity of the car?

Explanation:

Let the velocity of car be v . We shall apply doppler's effect . Here the car is running towards the observer .

f = f₀ x( )

Here f is apparent frequency f₀ is true frequency , V is velocity of sound and v is velocity of source .

Putting the values

860 = 800 x  340 / (340 - v )

1.075 = 340 /  (340 - v )

365.5 - 1.075 v = 340

25.5 = 1.075 v

v = 23.72 m /s

your answer is c! hope this : )