A car travels a certain distance from A to B at the speed of 20 km/hour and B to C at the speed of 30 km/hour. If the distance between A to B and B to C is 120 km. Find the average speed of the car in the whole journey.a)25 km/hourb)28 km/hourc)24 km/hourd)20 km/hourCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

When distance us halved the avg. speed is 2VU/V+U
where V and U are the speeds

Answer

GIVEN:
Speed of a Car from A to B = 20 km/hour
Speed of Car from B to C = 30 km/hour

CONCEPT:
If in these types of questions, the distance is same then we ignore the value of the distance.

FORMULA USED:
Average Speed = 2 × S1 × S2/S1 + S2

CALCULATION:
∴ Required Average speed = 2 × 20 × 30/20 + 30 = 24 km/hour

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