Concept:Speed: The distance travelled by the body in unit time.\(Speed = \frac{{Distance}}{{Time}}\)Also, \(Time= \frac{{Distance}}{{Speed}}\)Average Speed: Since the body does not always have the same speed, So we use the concept of average speed. It is the ratio of total distance covered to total time taken by the body.\(Average\;Speed = \frac{{Total\;Distance}}{{Total\;Time}}\)Calculation:StationDateArrivalDepartureSurat29th September 2019-20:45Nagarcoil1st October 201920:45-The person was on the train for 3 days.Total Distance covered = 2200kmTime taken on different daysOn 29th Oct = 3h 15minOn 30th Sept = 24 hrsOn 1st Oct = 12 h 15 minTotal time = 40 hrsAverage Speed = distance/ time = (2200/40) = 55km/h Thus, average speed of the train is 55km/h.