Multiple choice

A train travelling from A to B meets with an accident after 1 hour. After the accident, it moves at four-fifths of the former speed and arrives 2 hours late. If the train had covered 80 km more before the accident, then it would have been just 1.5 hours late. Find the original speed of the train.

  1. 60 kmph

  2. 40 kmph

  3. 80 kmph

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let original speed be v and distance be d. Time taken = 1 + (d-v)/0.8v = 1 + 2. If 80km more covered, time = 1 + 80/v + (d-v-80)/0.8v = 1 + 80/v + 1.5. Solving the system of equations for v gives 40 kmph.

AI explanation

Let the normal speed be v and the remaining distance after the accident be d. Moving at four-fifths of v causes a 2 hour delay, meaning the normal time d divided by v equals 8. If the train covers 80 km more before the accident, the remaining distance becomes d minus 80, and the 1.5 hour delay means (d minus 80) divided by v equals 6. Subtracting the second equation from the first gives 80 divided by v equals 2, so the original speed v is 40 kmph.

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