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: Total Distance = 1512 kmTotal time = 28 hrsWe know that,\(Average\;Speed = \frac{{Total\;Distance}}{{Total\;Time}}\)\(? Average\;Speed = \frac{{1512\;km}}{{28\;hr}}\)? Average Speed = 54 km/hr? Average Speed = 54 km/hr À” 5/18 = 15 m/s