Multiple choice

A train met with an accident 120 km away from station A. It completed the remaining journey at 4/5th of the original speed and reached station B, 1 hour 12 minutes late. Had the accident taken place 60 km further, the train would have been only 1 hour late. What was the original speed of the train?

  1. 60 km/hr

  2. 55 km/hr

  3. 65 km/hr

  4. 75 km/hr

  5. 70 km/hr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let original speed be V. Time saved by traveling 60 km at speed V instead of 0.8V is 12 minutes (0.2 hours). 60/(0.8V) - 60/V = 0.2. 75/V - 60/V = 0.2. 15/V = 0.2. V = 75 km/hr.

AI explanation

The difference in time caused by the 60 km difference in the accident location is 12 minutes, which is one-fifth of an hour. This means the train travels 60 km at its original speed in one-fifth of an hour less time than traveling 60 km at four-fifths of its original speed. The equation becomes 60 divided by four-fifths of the speed minus 60 divided by the speed equals one-fifth. Solving this equation, 75 divided by the speed minus 60 divided by the speed equals one-fifth, yielding 15 divided by the speed equals one-fifth, so the original speed is 75 km/hr.

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