Exam path · Time, Speed & Distance
Time speed and distance questions all come from one relationship: distance equals speed multiplied by time. Everything else in the topic is that relationship plus a units conversion or a relative speed. Fix the units first, decide whether the two objects are closing on each other or pulling apart, and the arithmetic that remains is a single multiplication or division.
Speed, distance and the train problems built on them are worth two to three marks in banking prelims and considerably more in railway papers, where the topic is a favourite. It is also where units quietly destroy otherwise correct work: a paper mixes km/h with metres and seconds within the same question, and a candidate who converts at the wrong moment gets a clean wrong answer that is on the option list.
Try it against the clock. Time, Speed & Distance runs at 40s easy, 50s medium and 65s hard. The clock is stamped and judged on our server, so the limit you see is the deadline that is actually enforced — and it starts when you tap Start, not while the question is loading.
Generated by the same engine that mints the ComputePrep daily. Each answer is computed from the numbers printed in the question, and the walkthrough below each one is the engine's own working — not a solution written afterwards. Reload this page's live drill and you get different numbers.
A car covers a certain distance at 12 km/h and returns along the same route at 36 km/h.
What is its average speed for the whole journey?
A train covers 320 km at a steady 80 km/h.
How long does the journey take?
A train covers 135 km at a steady 45 km/h.
How long does the journey take?
Multiply km/h by 5/18 to get m/s, and m/s by 18/5 to go back. Do it as the first line of working, never in the middle — a conversion applied halfway through is the single largest source of wrong answers in this topic.
Two objects moving towards each other or in opposite directions: add the speeds. Same direction, one overtaking the other: subtract. Everything about trains crossing, boats and races follows from picking the right one of those two.
A train crossing a pole covers its own length. Crossing a platform or another train, it covers its length plus the other length. Missing the second term is the classic train-question error.
For the same distance, time is inversely proportional to speed: raise speed in the ratio 3:4 and time falls in the ratio 4:3. That converts most "if he had walked faster" questions into one proportion instead of two equations.
| The situation | Distance to use |
|---|---|
| Train crosses a pole or a standing person | Length of the train |
| Train crosses a platform or a bridge | Train length + platform length |
| Two trains cross each other | Sum of both lengths, at the sum or difference of speeds |
| Boat downstream | Speed of boat + speed of stream |
| Boat upstream | Speed of boat − speed of stream |
The wrong options are not random numbers. Each one is the result of a specific careless error for this topic, so picking one tells you which habit is costing you marks.
A question that gives a speed in km/h and a length in metres wants an answer in seconds. Convert at the very start or the error compounds through every later step.
Same direction means the difference, opposite means the sum. Both answers appear in the options because both are the result of a defensible-looking reading of the sentence.
Going somewhere at 40 km/h and back at 60 does not average to 50. Equal distances at different speeds need the harmonic mean, which here is 48 — and 50 is always an option.
Multiply by 5/18. To go the other way, from m/s to km/h, multiply by 18/5. Doing this conversion as the first step of the working, rather than partway through, prevents most of the errors in this topic.
Add when the objects move towards each other or in opposite directions, subtract when they move in the same direction and one is overtaking. For boats, downstream adds the stream speed and upstream subtracts it.
Its own length plus the length of the platform. Crossing a pole or a stationary person, it covers only its own length. Forgetting the second term is the most common train-question mistake.
Between 40 and 65 seconds in prelims. The drill enforces 40 seconds on easy, 50 on medium and 65 on hard, stamped and judged on the server rather than in your browser.
The topic overlaps heavily, and RRB papers lean on speed, distance and time more than banking papers do. The arithmetic and the methods are identical, so this drill serves both.
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