A bus journey works out to an average speed of 50 km/h

Why

Daksh is reading 'average speed' the way the word 'average' usually gets used casually, as if it describes what was happening at every single moment along the way. But an average is calculated only from the total distance and the total time, smoothing every speed-up and slow-down of the whole trip into one single number — it doesn't require the speed to have actually been steady throughout. A bus averaging 50 km/h over a journey might have crawled at 20 km/h through a crowded market, waited at a red light doing 0 km/h, and then raced at 80 km/h on an open highway — all of that can still average out to 50, without the bus ever actually travelling at 50 for even one minute. Test: a student scoring an average of 70% across three tests might have gotten 40%, 90% and 80% — never once actually scoring 70 on any single test. Mother is right: an average speed describes the whole trip's overall result, not the speed at any one moment along the way.