The note D above middle C has a frequency of 294 cycles per second, and the note E has a

Question

frequency of 330 cycles per second. A driver of a moving car sounds the horn, which emits an E
tone, but a stationary observer hears a D tone. Calculate the speed at which the car is moving,
and state whether it is travelling towards or away from the observer.
I got 37.42 however it's supposed to be

Answer 1

Supposed to be 41.6m/s. And how can I tell if it's moving towards or away from the observer?

Answer 2

If you hear a lower frequency, longer wavelength, it is moving away

294 / 330= v/(v+343.7)
http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/dopp.html

Answer 3

I agree with 41.6 m/s if sound velocity is 343.7 m/s