A girl goes from M to N at a speed of 25 km/h and returns to M at a speed of 37.5 km/h, via the same route. What is the girl's average speed (in km/h)?
Answer & explanation
Correct answer: option 1
Average Speed = \(\frac{2 × S1 × S2 }{S1 + S2 }\)
= \(\frac{2 × 25 × 37.5 }{25 + 37.5 }\)
= \(\frac{2 × 25 × 37.5 }{62.5 }\)
= 30 km/h