A car passes point A driving at a constant rate of 60 km/h. A second car, traveling at a constant rate of 75 km/h, passes the same point A a while later and then follows the fist car. It catches the first car after traveling a distance of 75 km past point A. How many minutes after the first car passed point A did the second car pass point A?

Guest Jan 7, 2020

#1**+1 **

Call D the distance that the first car is from point A when the second car passes point A

Then the remaining time for the first car to travel 75 miles from point A must be

(75 - D) / 60

And since the second car catches the first car 75 km past point A and it travels at 75km/h it must take this car 1 hour to catch the first car after passing point A

So.....the time it takes the first car to travel (75 - D) km must be just 1 hour

So

(75 - D) / 60 = 1

D = 15

So...the first car is 15 km past point A when the second car reaches point A

So.....the time it takes the first car to travel 15 km = 15 minutes

So......the second car must pass point A 15 minutes after the first

CPhill Jan 7, 2020