to qualify for a race, a car must average 350 km/hr for four laps. If a driver averages 285 km/hr for the first two laps, what average speed must be achieved for the final two laps in order to qualify?

3 answers

avg speed=distance/time

350=4laps/(time2+time4)

time for first two time2=distance/285=2laps/285

time for last two laps=2laps/V

350=4/(2/285+2/V)

2/285+2/V=4/350

2/v=4/350-2/285

1/V=2/350-1/285

V=350*285/(2*285-350) and you can finish it.

453.41