A train travels 55 kilometers in 2 hours, and then 52 kilometers in 5 hours. What is its average speed?

The formula for working out speed is distance : time.

55 km : 2 hours = 27.5 km/h (average speed for first part of journey)

52km : 5 hours = 10.4 km/h (average speed for second part of journey)

(27.5 + 10.4) : 2 = 18.95 km/h (average speed throughout the journey)

Average speed = (total distance covered) / (time to cover the distance).

Total distance covered = (55 km + 52 km) = 107 km

Time to cover the distance = (2 hrs + 5 hrs) = 7 hrs

Average speed = (107 km) / (7 hrs)

Average speed = 15.29 km/hour