A bus goes to Akola from Mayapuri at a speed of 39 km/h for 70% of the journey, and covers the remaining past of its journey at the speed of 49 km/h.  What is the average speed of the bus (in km/h) during the entire journey under consideration?

42

70% = \(\frac{7}{10}\)

Speed      → 39            49

Distance   →  7             3

Avg. speed during the entire journey = \(\frac{39 × 7 + 49 × 3}{10}\)

                                                      = \(\frac{273 + 147}{10}\) = \(\frac{420}{10}\) = 42 km/h