Description : At what average speed did the car, if it covered the first 7.3 km in 5.2 minutes, then it drove 4.2 minutes at a speed of 8.3 km.h-1, then it stood for 1.2 minutes and finally it traveled 7.8 km in 1.5 minutes.
Last Answer : driving time (including stop) is 5.2 + 4.2 + 1.2 + 1.5 = 12.1 minutes in the first phase drove 7.3 km in the second phase drove 4.2 / 60 * 8.3 = 0.581 km in the third phase did not drive anything in ... 60 / 12.1 * 15.681 = 77, 75702 km average speed is 77.75702 km / h ... but I'm a bad accountant