Question

A car travels from A to B at a speed of $20km/hr$ and returns at a speed of $30km/hr$. The average speed of the car for the whole journey is

• A. $25km/hr$
• B. $24km/hr$
• C. $50km/hr$
• D. $5km/hr$

Answer 1

Answer: (B)

$24km/hr$

Answer 2

Distance average speed

$= \frac{2v_{1}v_{2}}{v_{1} + v_{2}}$ $= \frac{2 \times 20 \times 30}{20 + 30}$ $= \frac{120}{5} = 24\mspace{6mu} km/hr$