If a man travels at $\frac{1}{x}$ km/h on a journey and returns at $\frac{1}{x^2}$ km/h, then his average speed for the journey is:
Answer & explanation
Correct answer: option 2
Average speed = \(\frac{2 \;×\;speed1\;×\;speed2 }{speed1 \;+\;speed2}\)
Average speed = \(\frac{2 \;×\;1/x\;×\;1/x^2 }{1/x \;+\;1/x^2}\)
= \(\frac{2 }{x\;+\;x^2}\)
The average speed is \(\frac{2 }{x\;+\;x^2}\)