The train covered 60 km in 1 hour. Then he drove for another 0.5 hours at a speed of 90 km / h.

The train covered 60 km in 1 hour. Then he drove for another 0.5 hours at a speed of 90 km / h. What is the average speed of the train?

Let us determine what total time the conditional train was in motion, when in this case we know, in accordance with the available data in the condition of the problem, that at first it went 1 hour, and then another half hour:

1 + 0.5 = 1.5.

Let us determine the total distance that he traveled for the entire time when we know for sure that initially, that in the second section he was moving at a speed of 90 km / h:

60 + 0.5 * 90 = 105.

Let us determine what its average speed will be equal to in this case:

105: 1.5 = 70.

Answer: 70 km / h.