<u>The average speed</u> of the train for the trip is equal to 
Why?
To calculate the average speed, we need to divide the trip into three moments:
- First moment, the train traveled 120 km at a speed of 60 km/h.
- Second moment, the train stopped for 0.5 hours, meaning that the train did not travel for that time (traveled distance equal to 0 km).
- Third moment, the train traveled 180 km at a speed of 90 km/h.
We can use the following formula to calculate the average speed:

So, for our problem we have:

From the statement, we know that:

Calculating the times, we have:



Then, substituting the times into the main equation, we have:

Hence, we have that <u>the average speed</u> of the train for the trip is equal to 
Have a nice day!