UPSC Prelims 2016·CSAT·Quantitative Aptitude·Time, Speed and Distance

A daily train is to be introduced between station A and station B starting from each end at 6 AM and the journey is to be completed in 42 hours. What is the number of trains needed in order to maintain the Shuttle Service?

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Last updated 23 May 2026, 3:31 pm IST
  1. A2Correct
  2. B3
  3. C4
  4. D7

Explanation

To determine the number of trains required, we look at the time cycle of a single train. 1. A train starts from Station A at 6 AM on Day 1. 2. It completes its journey and reaches Station B 42 hours later, which is 12 midnight on Day 2. 3. This same train is now at Station B and can be used for the 6 AM departure from Station B on Day 3. To maintain a daily service starting at 6 AM from both ends: Train 1 starts from Station A at 6 AM on Day 1. Train 2 starts from Station B at 6 AM on Day 1. By the time the next departure is needed from Station A on Day 2, Train 2 is still in transit to Station A. Therefore, Train 2 will arrive at Station A at midnight and be ready for the Day 3 departure. This creates a rotation where only 2 trains are needed to cover the schedule indefinitely, as the train arriving at one station is always ready for the next available 6 AM slot. The correct answer is A.
Quantitative Aptitude: A daily train is to be introduced between station A and station B starting from each end at 6 AM and the journey is to b
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