Given: A person goes from a place to another place with the speed = 30 km/hr The person returns to his place with the speed = 50 km/hr Formula: If in these types of questions, the distance is same then Average Speed =(2×S1×S2)/(S1+S2) Where, S1 is the speed from A to B and S2 is the speed from B to A Calculation: Average speed =(2×S1×S2)/(S1+S2) =(2×30×50)/30+50 = 37.5 km/hr