Question

Abdul, while driving to school, computes the average speed for his trip to be 20 kmh^-1 On his return trip along the same route, there is less traffic and the average speed is 30 kmh^-1 . What is the average speed of Abdul’s trip? 

Answer 1

Let one side distance = x km. 

Time taken for forward trip at a speed of 20 km/h = Distance / Speed = x/20 h. 

Time taken in return trip at a speed of 30 km/h = x/30 h.

Total time for the whole trip = / 20 + / 30 = 3+2 /60 = 5 60 h. 

Total distance covered = 2x km. 

We know, Average speed = Total distance ÷ Total time 

                                          = 2x ÷ (5x/60) = 24 kmh^-1 .