A car travels from $A$ to $B$ at a speed of $10 km/hr$ and returns at a speed of $30 km/hr$ . The average speed of the car for the whole journey is

15 km/hr

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20 km/hr

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25 km/hr

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30 km/hr

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Solution

The correct option is A $15 km/hr$
If the distance travelled is same, then
$average speed = \frac{2 v_{1} v_{2}}{v_{1} + v_{2}} = \frac{2 \times 10 \times 30}{10 + 30}$
$= \frac{600}{40} = 15 km/hr$

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A car travels from A to B at a speed of 10 km/hr and returns at a speed of 30 km/hr. The average speed of the car for the whole journey is

The correct option is A 15 km/hrIf the distance travelled is same, then average speed =2v1v2v1+v2=2×10×3010+30 =60040=15 km/hr

A car travels from $A$ to $B$ at a speed of $10 km/hr$ and returns at a speed of $30 km/hr$ . The average speed of the car for the whole journey is

The correct option is A $15 km/hr$
If the distance travelled is same, then
$average speed = \frac{2 v_{1} v_{2}}{v_{1} + v_{2}} = \frac{2 \times 10 \times 30}{10 + 30}$
$= \frac{600}{40} = 15 km/hr$