Multiple choice

A couple drives in a car from place A to place B. For 2/3 of the distance between places A and B, the husband drives at 40 km/hr and for the remaining distance he drives at 60 km/hr. Find the average speed of the car.

  1. 45 km/hr

  2. 50 km/hr

  3. 52.5 km/hr

  4. 48 km/hr

  5. None of these
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A Correct answer
Explanation

Average speed = Total distance / Total time. Let total distance be 3D. Time = (2D/40) + (D/60) = D/20 + D/60 = 4D/60 = D/15. Average speed = 3D / (D/15) = 45 km/hr.

AI explanation

Assume the total distance between places A and B is 120 kilometers, meaning the husband drives 80 kilometers at 40 km/hr and the remaining 40 kilometers at 60 km/hr. The time taken for the first part is 80 / 40 = 2 hours, and the time for the second part is 40 / 60 = 2/3 hours. Using the average speed formula Total Distance / Total Time, we get 120 / (2 + 2/3), which equals 120 / (8/3) = 45 km/hr. The average speed of the car is 45 km/hr.

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