Average Velocity - The average velocity of a body is the total displacement travelled by the total time taken to cover this distance. 
 Average velocity= Total Displacement/Total Time taken 
Avg. Velocity (vavg) = (Initial velocity + Final velocity)/2 = (u+v)/2 
where, u = initial velocity, v = final velocity  

Example 1: During first half of a journey by a body it travel with a speed of 40 km/hr and in the next half it travels with a speed of 20 km/hr. Calculate the average speed of the whole journey.

Example 2 : If Ananya was able to travel 6 km in North in 2 hour in his car. What was her velocity?

Example 3: A car travels 20 km in first hour, 40 km in second hour and 30 km in third hour. Calculat the average speed of the train.