Multiple choice

A person covers a distance of 100 km in 10 hours partly by walking at 7 kmph and the rest by running at 12 kmph. Find the distance covered in each part.

  1. 72

  2. 80

  3. 75

  4. 70
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let distance walked be d. Distance run is 100-d. Time = d/7 + (100-d)/12 = 10. Multiply by 84: 12d + 7(100-d) = 840. 12d + 700 - 7d = 840. 5d = 140. d = 28. Running distance = 100 - 28 = 72.

AI explanation

Assume the distance covered by walking is d kilometers; the time taken to walk is d/7 hours and the time taken to run the remaining (100 - d) kilometers is (100 - d)/12 hours. Since the total time is 10 hours, we write the equation d/7 + (100 - d)/12 = 10. Multiplying the entire equation by the least common multiple of 84 gives 12d + 7(100 - d) = 840, which simplifies to 5d + 700 = 840, yielding d = 28. The question likely asks for the running distance, which is 100 - 28 = 72 km. The distance covered by running is 72 km.

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