Question

You are driving on a Canadian freeway to a town that is 200 kilometers from your home. After 30 minutes you pass a freeway exit that you know is 50 kilometers from your home. Assuming that you continue at the same constant speed, how long will it take for the entire trip?

I did:
50km/30min = 120km/h
200*30/ 50 =h
120 =h

but I got 120 mins wrong.

Answer 1

first, 50km/30min = 100km/hr
so, 200 km takes 2 hr
that's 120 min, but maybe they wanted the time in hours.

you are kind of sloppy with the units in your calculations, switching back and forth between minutes and hours.

Answer 2

thanks oobleck

Answer 3

50km/0.5h = 100 km/h.

T = (200-50)/100 = 1.5 h.