Two cars leave a school at the same time. One travels north at 60mph and the other travels south at 45mph. In how many hours will they be 420 miles apart?

Answer 1

The distance each car travels per hour is 60t and 45t respectively.

Per the pythagorean theorem, The distance function is

sqrt ( (60t)^2 + (45t)^2 ) =

sqrt( 3600t^2 + 2025t^2 ) =

sqrt( 5625*t^2) =

75t

420 = 75t

420/75 = 5.6 hours

5 hours and 36 minutes