A bus travels at a speed of 50 km per hour to go from its origin to its destination at a distance of 300 km and travels at a speed of 60 km per hour to return to the origin. What is the average speed of the bus?

The average speed of an object is defined as the total distance covered divided by the total time taken [1]. In this scenario, the bus travels a distance of 300 km at 50 km/h and returns the same 300 km at 60 km/h. The time taken for the onward journey is 6 hours (300/50), and the return journey takes 5 hours (300/60). The total distance is 600 km, and the total time is 11 hours. Thus, the average speed is 600/11, which equals approximately 54.5454... km/h, rounded to 54.55 km/h. Alternatively, when distances are equal, the average speed is the harmonic mean of the speeds: (2 * v1 * v2) / (v1 + v2). Substituting the values: (2 * 50 * 60) / (50 + 60) = 6000 / 110 = 54.55 km/h.

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 8: Measurement of Time and Motion > 8.3 Speed > p. 113