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What is the average speed of a car which covers half the distance with a speed of 28 km/h and the other half with a speed of 84 km/h?

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  1. 43km/h
  2. 39km/h
  3. 38km/h
  4. 42km/h

Answer (Detailed Solution Below)

Option 4 : 42km/h
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Detailed Solution

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Given:

Speed for half the distance (S1) = 28 km/h

Speed for the other half (S2) = 84 km/h

Formula used:

Average Speed = 2 × S1 × S2 / (S1 + S2)

Calculations:

Average Speed = 2 × 28 × 84 / (28 + 84)

⇒ Average Speed = 2 × 28 × 84 / 112

⇒ Average Speed = 2 × 21

⇒ Average Speed = 42 km/h

∴ The correct answer is option (4).

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