Multiple choice

A man travels at 40 km/hr for 50% of his journey and increases his speed by 100% for the rest of the journey. Find the total distance if he completes the journey in 1.5 hours.

  1. 80 km

  2. 100 km

  3. 120 km

  4. 75 km

  5. None of these
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A Correct answer
Explanation

Let total distance be D. Half is D/2. Time = (D/2)/40 + (D/2)/80 = 1.5. D/80 + D/160 = 1.5. (2D+D)/160 = 1.5. 3D = 240, D = 80 km.

AI explanation

Let the total distance be d kilometers, so 50 percent of the journey is 0.5d. The time for the first half is 0.5d divided by 40, and the speed for the second half increases by 100 percent to 80 km/hr, giving a time of 0.5d divided by 80. The sum of these times equals 1.5 hours, so (d/80) + (d/160) equals 1.5. Solving 3d/160 = 1.5 gives d = 80, meaning the total distance is 80 km.

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