A person takes a trip, driving with a constant speed of 89.5 km/h, except for a 22.0-min rest stop. If the person’s average speed is 77.8 km/h

Question

(a) how much time is spent on the trip and

(b) how far does the person travel?

Answer 1

The total time for the trip is D/89.5 + 22/60 where D is the unknown distance. The total time is also given by D/77.8. These two equations can be equated to give D/89.5 +22/60 = D/77.8. This can be solved for D to get the distance. I got D = 216 miles. The total time is 216/77.8 = 2.78 hours. The essential thing to understand is that during the 22 min rest stop, the distance travelled is zero.