Mr. G. travel by car from one city to another. He drives 30.0 minutes at 80.0 km/h, 12.0 minutes at 105 km. h and 45.0 minutes at 40.0 km/h. He also spends 15.0 minutes eating lunch at a rest stop. What is the average speed for the entire trip?

53.5 km/h

Step-by-step explanation:

Average speed = distance / time

Total time in hours = 30/60 + 12/60 + 45/60 + 15/60

= 0.5 + 0.2 + 0.75 + 0.25

= 1.7 hours

Distance = Speed / time

Total distance covered = (0.5*80) + (0.2*105) + (0.75*40)

= 40 + 21 + 30

= 91 km

Average speed of the entire trip = 91/1.7

= 53.5 km / h