Question

A car moves from $A$ to $B$ with a speed of $30 \,kmph$ and from $B$ to $A$ with a speed of $20\,kmph$. What is the average speed of the car ?

• A. 25 km/h
• B. 24 km/h
• C. 50 km/h
• D. 10 km/h

Answer 1

Answer: (B)

24 km/h

Answer 2

The correct option is(B): 24 km/h.

We have given that
Speed of Ist car
$v_{1}=30\, km / h$
Speed of IInd car
$v_{2}=20\, km / h$
The average speed of the car
$=\frac{2 v_{1} v_{2}}{v_{1}+v_{2}}=\frac{2 \times 30 \times 20}{30+20}$
$=\frac{1200}{50}=24\, km / h$