Speed Distance Time Questions: How to Master Them in Aptitude Tests
Speed, distance, and time questions are a staple of numerical reasoning assessments used by employers across every major industry. Whether you are applying to Google, Deloitte, Unilever, JP Morgan, or the Civil Service, there is a strong chance your aptitude test will include at least one problem that requires you to calculate how far, how fast, or how long. These questions test more than basic arithmetic. They measure your ability to select the right formula, convert between units under pressure, and interpret real-world scenarios quickly and accurately.
This guide walks you through the core formula, the most common question types, the unit conversion traps that catch candidates out, and the practice strategies that build genuine speed and confidence. If you can master these fundamentals, you will handle SDT questions faster than most of your competition.
The Speed Distance Time Formula Explained
Every speed, distance, and time question rests on a single relationship: Speed = Distance / Time. From this one equation, you can derive the other two variations you need. Distance = Speed x Time gives you the total ground covered. Time = Distance / Speed tells you how long a journey takes.
A helpful memory aid is the SDT triangle. Picture a triangle divided into three sections, with Distance on top and Speed and Time on the bottom. Cover the variable you want to find, and the remaining two show you whether to multiply or divide. If you cover Distance, you see Speed x Time. If you cover Speed, you see Distance / Time. If you cover Time, you see Distance / Speed.
This triangle is not just a revision trick. Under the time pressure of a real aptitude test, having an instant visual reference for the formula prevents the kind of second-guessing that wastes precious seconds. Employers like JP Morgan and Deloitte use numerical reasoning tests where every question counts, and hesitation on a straightforward formula question is a costly mistake.
Here is a worked example. A delivery driver travels 150 kilometres in 2.5 hours. What is the average speed? Apply the formula: Speed = 150 / 2.5 = 60 km/h. Straightforward, but the key is recognising which formula variation to use and applying it without hesitation.
💡Every SDT question uses the same core relationship. Memorise the triangle, practise until the formula selection is automatic, and you will save valuable seconds on every question.
Unit Conversions: The Trap That Catches Most Candidates
Unit conversion is where most candidates lose marks on speed, distance, and time questions. The formula itself is simple, but if you plug in kilometres when the speed is in metres per second, your answer will be wrong by a factor of a thousand. Test designers at companies like SHL and Aon know this, and they deliberately mix units to separate careful candidates from careless ones.
Here are the conversions you need to know by heart:
| Conversion | Formula | Example |
|---|---|---|
| km/h to m/s | Divide by 3.6 (or multiply by 5/18) | 72 km/h = 20 m/s |
| m/s to km/h | Multiply by 3.6 (or multiply by 18/5) | 25 m/s = 90 km/h |
| Hours to minutes | Multiply by 60 | 2.5 hours = 150 minutes |
| Minutes to hours | Divide by 60 | 45 minutes = 0.75 hours |
| Kilometres to metres | Multiply by 1000 | 3.2 km = 3200 m |
| Miles to kilometres | Multiply by 1.609 | 10 miles = 16.09 km |
The golden rule is simple: before you touch the formula, check that all three values use compatible units. If speed is in km/h, distance must be in km and time must be in hours. If speed is in m/s, distance must be in metres and time must be in seconds.
A common test scenario gives you a train travelling at 90 km/h and asks how far it travels in 20 minutes. The trap is that 20 minutes is not 20 hours. Convert first: 20 minutes = 20/60 = 1/3 of an hour. Then calculate: Distance = 90 x (1/3) = 30 km. Candidates who skip the conversion step and multiply 90 by 20 get 1800, which is not even close to reality.
💡Unit conversion errors are the single biggest source of wrong answers on SDT questions. Always convert before you calculate, and double-check that your answer makes real-world sense.
Average Speed: Why Simple Averaging Does Not Work
Average speed questions trip up even well-prepared candidates because the intuitive approach is wrong. If you drive 60 km/h for the first half of a journey and 120 km/h for the second half, the average speed is not 90 km/h. This is one of the most tested concepts in numerical reasoning assessments at employers like Google and the Civil Service.
The correct formula is: Average Speed = Total Distance / Total Time.
Consider this example. A cyclist rides 30 km at 15 km/h and then 30 km at 10 km/h. The first leg takes 30/15 = 2 hours. The second leg takes 30/10 = 3 hours. Total distance is 60 km. Total time is 5 hours. Average speed = 60/5 = 12 km/h. Notice this is not the arithmetic mean of 15 and 10, which would be 12.5. The difference is small here but can be dramatic when the speed difference between legs is large.
The reason simple averaging fails is that you spend more time at the slower speed. Time is not equally distributed across the two speeds, so the slower speed pulls the average down more than you might expect. This is a concept that connects directly to ratio and proportion skills, which are tested throughout numerical reasoning assessments.
Here is a comparison of the two methods applied to the same journey:
| Scenario | Simple Average | Correct Average (Total Distance / Total Time) |
|---|---|---|
| 60 km at 60 km/h + 60 km at 120 km/h | 90 km/h | 80 km/h |
| 30 km at 15 km/h + 30 km at 10 km/h | 12.5 km/h | 12 km/h |
| 100 km at 50 km/h + 100 km at 100 km/h | 75 km/h | 66.7 km/h |
| 200 km at 80 km/h + 200 km at 40 km/h | 60 km/h | 53.3 km/h |
The pattern is clear. The correct average speed is always lower than the simple arithmetic mean when the two speeds differ. The greater the difference between the speeds, the larger the gap between the two methods.
💡Never average the speeds directly. Always calculate total distance divided by total time. This is one of the most commonly tested traps in aptitude tests used by employers like Unilever and JP Morgan.
Relative Speed: Moving Towards and Away
Relative speed questions involve two objects moving simultaneously. The principle is straightforward: when two objects move towards each other, their relative speed is the sum of their individual speeds. When they move in the same direction, the relative speed is the difference.
Imagine two trains departing from cities 300 km apart, heading towards each other. Train A travels at 80 km/h and Train B at 70 km/h. Their relative speed is 80 + 70 = 150 km/h. Time to meet = 300/150 = 2 hours. If both trains were heading in the same direction with Train A behind, the relative speed would be 80 - 70 = 10 km/h, and Train A would take 300/10 = 30 hours to catch up.
Employers like the Civil Service and Deloitte include relative speed questions because they test whether candidates can identify the correct operation (addition or subtraction) based on the scenario described. The arithmetic is not difficult, but misreading the direction of travel turns an easy question into a wrong answer.
A practical approach for these questions is to sketch a quick diagram. Draw two arrows showing the direction of travel. If the arrows point towards each other, add the speeds. If they point the same way, subtract. This takes five seconds and virtually eliminates directional errors.
Relative speed concepts also appear in overtaking scenarios. If a car travelling at 100 km/h needs to overtake a truck travelling at 60 km/h, the car closes the gap at a relative speed of 40 km/h. Knowing the length of both vehicles and the gap between them lets you calculate exactly how long the overtaking manoeuvre takes.
Worked Examples and Practice Strategies
Working through examples under timed conditions is the most effective way to build speed and accuracy on SDT questions. Here are three progressively challenging problems that mirror what you will see in real aptitude tests.
Example 1: Basic formula application. A runner completes a 10 km race in 50 minutes. What is her speed in km/h? First, convert time: 50 minutes = 50/60 = 5/6 hours. Then apply the formula: Speed = 10 / (5/6) = 10 x (6/5) = 12 km/h.
Example 2: Multi-step with unit conversion. A car travels at 108 km/h. How many metres does it cover in 15 seconds? Convert speed: 108 km/h = 108/3.6 = 30 m/s. Calculate distance: 30 x 15 = 450 metres.
Example 3: Average speed with three legs. A salesperson drives 120 km at 60 km/h, then 90 km at 45 km/h, then 60 km at 30 km/h. What is the average speed for the entire journey? Leg 1: 120/60 = 2 hours. Leg 2: 90/45 = 2 hours. Leg 3: 60/30 = 2 hours. Total distance = 270 km. Total time = 6 hours. Average speed = 270/6 = 45 km/h.
The best preparation strategy combines formula drilling with full-length timed practice. Start by solving 20 to 30 SDT problems without a timer to build accuracy. Then gradually introduce time pressure until you can solve each problem in under 90 seconds. This approach mirrors how candidates prepare for assessments at firms like Google and Unilever.
For broader numerical reasoning preparation, work through data interpretation questions and percentage problems alongside your SDT practice. These topics share the same underlying skills of ratio manipulation and unit awareness.
Practise with realistic numerical reasoning tests to build the speed and accuracy you need for test day.
Common Mistakes and How to Avoid Them
Understanding where candidates go wrong is just as valuable as knowing the correct method. Here are the five most frequent errors on SDT questions and how to prevent each one.
Mixing units without converting. This is the number one mistake. Always scan the question for mismatched units before you start calculating. Circle or underline the units in the question text to make mismatches obvious.
Averaging speeds instead of using total distance over total time. As covered above, this produces wrong answers every time the speeds differ. Train yourself to reach for the correct formula automatically.
Confusing relative speed direction. Adding speeds when you should subtract, or vice versa. Draw a quick sketch showing the direction of travel before selecting your operation.
Rounding too early. Rounding intermediate values introduces cumulative errors. Keep at least two decimal places throughout your working and only round the final answer.
Misreading the question. Some questions ask for speed when you calculated time, or ask for the answer in a specific unit that differs from your working. Read the question twice: once before calculating and once before selecting your answer.
💡Most SDT errors are not caused by a lack of mathematical ability. They come from rushing, skipping the unit check, or misreading what the question actually asks. A disciplined approach eliminates these mistakes.
Start building your numerical reasoning skills today with practice tests that mirror the format and difficulty of real employer assessments.
Frequently Asked Questions
How do I handle mixed units such as minutes and hours?
Convert everything to the same unit before you calculate. For example, if a question gives speed in km/h and time in minutes, convert the time to hours by dividing by 60. Alternatively, convert the speed to km/min by dividing by 60 and keep the time in minutes. The key is consistency. It does not matter which unit you choose, as long as speed, distance, and time all align. A common approach is to convert everything to the larger unit (hours rather than minutes, kilometres rather than metres) because this tends to produce more manageable numbers.
What if the question gives speed in m/s and distance in km?
Convert one value to match the other before applying the formula. To convert m/s to km/h, multiply by 3.6. To convert km to metres, multiply by 1000. Employers like Deloitte and JP Morgan deliberately mix units in their numerical reasoning tests to assess whether candidates can identify and resolve mismatches. Practise the common conversions until they are automatic, and always check that your final answer uses the unit specified in the question.
Are speed distance time questions common in all aptitude tests?
SDT questions appear most frequently in numerical reasoning tests, which are a core component of assessment batteries used by Google, Unilever, the Civil Service, and most major graduate employers. They reinforce ratio and proportion skills because speed is effectively a rate: distance per unit of time. If your assessment includes any numerical reasoning section, you should prepare for SDT problems. They also appear in some mechanical reasoning and spatial awareness tests, particularly for engineering and technical roles.
Can I use a calculator for speed distance time questions?
This depends entirely on the test provider and the employer. Many numerical reasoning tests from SHL and Aon provide an on-screen calculator. Some employers, particularly for roles that require strong mental arithmetic such as trading positions at JP Morgan, deliberately restrict calculator access. Your invitation email will specify what tools are permitted. Regardless of calculator availability, practising mental shortcuts for common conversions, such as knowing that dividing by 3.6 converts km/h to m/s, saves time and reduces errors.
What is the most common mistake candidates make on SDT questions?
The most frequent error is failing to convert units before applying the formula. Candidates plug kilometres into a formula that requires metres, or use minutes when the speed is expressed per hour, and produce answers that are wildly incorrect. The second most common mistake is averaging speeds arithmetically instead of using total distance divided by total time. Both errors are completely preventable with a disciplined approach: check units first, apply the correct formula second, and verify that your answer makes real-world sense.
How much time should I spend on each SDT question during the test?
Most numerical reasoning tests allocate roughly 60 to 90 seconds per question. For straightforward single-step SDT problems, aim to finish in under 60 seconds. For multi-step problems involving unit conversions or average speed calculations, budget up to 90 seconds. If you find yourself spending more than two minutes on a single question, make your best estimate and move on. Practising under timed conditions is the most effective way to build the speed you need. Work through timed numerical reasoning practice to develop your pacing skills.
Start Practising Speed Distance Time Questions Today
Speed, distance, and time questions reward preparation more than almost any other question type in numerical reasoning tests. The formula is simple, the conversions are finite, and the question patterns are predictable. Candidates who invest a few hours in focused practice consistently outperform those who rely on remembering secondary school mathematics.
The employers who use these questions, from Google and Deloitte to Unilever, JP Morgan, and the Civil Service, are not trying to find mathematical geniuses. They are looking for candidates who can apply basic principles accurately under time pressure. That is a skill you can build through deliberate practice.
Get started with the complete numerical reasoning test package and build the speed, accuracy, and confidence you need to perform at your best on test day.