Hello. I have done these questions for physics. I don't know whether my answer is right or wrong. Could you please

Hello. I have done these questions for physics. I don't know whether my answer is right or wrong. Could you please

check for these answers please? If there is something wrong, could you please upload the correct solutions and I can understand what part that I did incorrect. 

SOLUTION TO QUESTIONS 5 &6 Keeping in mind that this is a Doppler Effect problem, hence without further derivation and thesymbols used bearing their usual meaning, the speed of the car, v from...