Question

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

• A. 42.5 km/hr
• B. 40.0 km/hr
• C. 37.5 km/hr
• D. 35.0 km/hr

Answer 1

Answer: (C)

37.5 km/hr

Answer 2

Distance average speed $= \frac{2v_{1}v_{2}}{v_{1} + v_{2}} = \frac{2 \times 30 \times 50}{30 + 50}$

$= \frac{75}{2} = 37.5\mspace{6mu} km/hr$