Answer:
The ratio is 1.03
Step-by-step explanation:
The ratio of the frequency that is heard while the car is approaching
to the frequency that is heard while the car is moving away
can be calculated using the Doppler effect equation:

where
: is the emitted frequency,
: is the speed of sound,
: is the speed of the receptor and
: is the emissor speed
Therefore the ratio is 1.03.
I hope it helps you!