Multiple choice

A car driver travels from the plains to the hill station which are $200$ km apart at an average speed of $40$ km/hr. In the return trip he covers the same distance at an average speed of $20$ km/hr. The average speed of the car over the entire distance of $400$ km is

  1. $25$ km/hr
  2. $26.67$ km/hr
  3. $28.56$ km/hr
  4. $30$ km/hr
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B Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 200 + 200 = 400 km. Time 1 = 200/40 = 5 hours. Time 2 = 200/20 = 10 hours. Total time = 15 hours. Average speed = 400 / 15 = 26.67 km/hr.

AI explanation

Using the average speed formula for equal distances, Average Speed = 2xy / (x + y), where x is 40 km/hr and y is 20 km/hr. The calculation is (2 * 40 * 20) / (40 + 20) = 1600 / 60. This simplifies to 26.67 km/hr. The result is 26.67 km/hr.

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