Explanation
Let the total distance be x km . The man covers half the distance at 6 km/hr, so the time taken to cover this half is: Time = Distance / Speed = (x/2) / 6 = x/12 The man covers the remaining half at 3 km/hr, so the time taken to cover this half is: Time = Distance / Speed = (x/2) / 3 = x/6 The total time taken to cover the entire distance is the sum of the times taken to cover each half : Total Time = x/12 + x/6 To add these fractions, we need a common denominator, which is 12. So we can rewrite the fractions as: Total Time = x/12 + 2x/12 = 3x/12 = x/4 Now, we can find the average speed: Average Speed = Total Distance / Total Time = x / (x/4) = 4 km/hr So, the correct answer is: 4 km/hr
