The average speed of a train running at a speed of 30 km/h during the first 150 km, at the speed of 50 km/h during the second 150 km and at the speed of 75 km/h during the last 150 km is nearly?

45

Avg. Speed = \(\frac{Total Distance}{Total Time}\) = \(\frac{150 + 150 + 150}{(150/30) + (150/50) + (150/75)}\) = \(\frac{450}{5 + 3 + 2}\) = 45 km/h