A car travels the first half of a distance between two places at a speed of 30 km/hr and the second half of the distance at 50 km/hr. The average speed of the car for the whole journey is
37.5 km/hr
vavg=dd2v1+d2v2
=2v1v2v1+v2
=2×30×5030+50
= 752
=37.5km/hr