1. The car is moving for one minute at a speed of 72km / h and then 600 meters at a speed of 54km / h. Calculate the total distance traveled and its mean speed.
2. The train was moving for half an hour at a speed of 60 km / h, then it crossed 15 km at a speed of 90 km / h and the next 10 km it crossed in 15 minutes. Determine the average speed of the train all the way, the total time and the total distance.
3. The motorcyclist was moving at the speed of 20 km / h for the first third of the time, he slowed down to the second third at 12 km / h. At what speed should he drive the last third of the way to arrive on time as if his average speed was 20km / h?​