A man covers the journey from station A to station B at a uniform speed of 36 kmph and returns to A with a uniform speed of 45 kmph, his average speed for the whole journey is:

Solution (By Examveda Team)

Average speed for this case is given by,
$$ {\frac{{2xy}}{{x + y}}} ,$$   where X and Y are two different speeds.
Average speed,
$$\eqalign{ & = {\frac{{2 \times 36 \times 45}}{{36 + 45}}} \cr & = \frac{{36 \times 90}}{{81}} \cr & = 40\,\,{\text{kmph}} \cr} $$