Question #ed6fb

1 Answer

Answer:

#170/7# km/h.

Explanation:

The Average velocity which is needed to qualify for the race : 200 km/h.

Let the distance for each lap be #x# km.
The Total distance is = #4x# km.

then total time taken to finish the race at average velocity 200km/h is = #(4x)/200# h.
If average velocity decraeses to 170 km/h,
then Total time taken to cover two laps = #(2x)/170# h.

Remaining time to finish and qualify for the race is = #{(4x)/(200) - (2x)/170} = {(4x * 170) - (2x * 200)}/3400 = (280x)/3400 = (7x)/85# h.

So the average velocity to complete and qualify for the race is =

#(2x * 85)/(7x) = 170/7# km/h.