Question

A train travels 20 km at a uniform speed of 60 kmh and next 20 km at a uniform speed of 80 km h calculate its average speed

Answer 1

time taken to travel 20 km at 60km/hr=20/60=0.33hr
time taken to travel nxt 20 km at 80km/hr=20/80=0.25hr
avg speed=total distance travelled / total time taken=40/0.58=68.96km/hr
                                                                                                ≈69km/hr

Answer 2

avg speed=total distance travelled / total time taken=40/0.58=68.96km/hr=69.00 km/hr