A man goes from place A to B at a speed of 12 km/h and returns from B to A at a speed of 18 km/h. His average speed for the entire journey is:
Answer & explanation
Correct answer: option 1
Average speed = \(\frac{2 × S1 × S2 }{S1 + S2}\)
= \(\frac{2 × 12 × 18 }{12 + 18}\)
= \(\frac{432 }{30}\)
= 14.4 km/h