Roshni travelled at the speed of 66 km/h while going from point A to point B and returned via the same route at the speed of 92.4 km/h. What was Roshni’s overall average speed during the two-way journey?

77 km/h

Average Speed = \(\frac{2 × S1 × S2 }{S1 + S2}\)

= \(\frac{2 × 66 × 92.4 }{66 + 92.4}\)

= \(\frac{2 × 66 × 92.4 }{158.4}\)

= 77 km/h

So , the average speed during whole journey is 77 km/h