Answer:
The value is
Explanation:
From the question we are told that
The distance of friends house from your point is 
The distance of your friends street from your street is 
The diagram illustrating this question is shown on the first uploaded image
From the diagram we can apply by Pythagoras theorem as follows

=>
=>
=>
<span>So we want to know what will happen when the fast moving car that is making loud noise that is initially approaching the person, passes the person and starts to move away. So Doppler effect is a phenomenon where when the source of a sound is approaching a person, the person hears the sound as higher than if the source was standing still with respect to the person because the wavelength is getting shorter, and as the source is moving avay from the person the sound is getting deeper because the wavelength is getting longer. So the correct answer is A. </span>
The train travells at he speed of 225 km/2.5h
now
225km=225000m
2.5 hr=150min=9000s
=>avg sp of train is=225000/9000s=25m/s