Speed Time and Distance Tricks for SSC CGL: The Short Answer
Every speed, time and distance question rests on one formula: Distance = Speed × Time. The tricks that save time in SSC CGL are: convert km/h to m/s by multiplying by 5/18, use 2xy/(x + y) for average speed over equal distances, add speeds when objects move towards each other and subtract them when they move the same way, and in train questions add the lengths of whatever the train has to cross.
Key takeaway for SSC: SSC CGL Tier 1 usually has 1 to 2 questions from speed, time and distance (including trains), and SSC CHSL, MTS and bank Clerk exams ask the same patterns. Learn the eight formulas in the revision table and the ratio method; most questions then take under a minute. Every answer here was computed in Python.
This chapter links closely to work and ratio, so keep our time and work tricks for SSC CGL and ratio and proportion for SSC CGL notes open alongside.
Speed Time and Distance Formula (Basic Relationship)
| Find | Formula |
|---|---|
| Distance | Speed × Time |
| Speed | Distance ÷ Time |
| Time | Distance ÷ Speed |
Example 1: A car covers 360 km in 4.5 hours. Find its speed.
Speed = 360 ÷ 4.5 = 80 km/h.
Units must match. If speed is in km/h, time must be in hours; if speed is in m/s, distance must be in metres.
How to Convert km/h to m/s (5/18 Trick)
| Convert | Multiply by | Example |
|---|---|---|
| km/h → m/s | 5/18 | 72 km/h × 5/18 = 20 m/s |
| m/s → km/h | 18/5 | 15 m/s × 18/5 = 54 km/h |
Why 5/18? 1 km/h = 1,000 m ÷ 3,600 s = 5/18 m/s.
Learn these pairs by heart: 18 km/h = 5 m/s, 36 = 10, 54 = 15, 72 = 20, 90 = 25, 108 = 30.
Speed Time and Distance Ratio Trick (Direct and Inverse)
- For a fixed time, distance ∝ speed.
- For a fixed distance, time ∝ 1/speed. If speeds are in the ratio a : b, times are in the ratio b : a.
Example 2: The ratio of two speeds is 3 : 4. The slower person takes 20 minutes more for the same journey. Find the time taken by the faster person.
Times are in the ratio 4 : 3. The difference of 1 unit = 20 minutes, so the faster person takes 3 × 20 = 60 minutes (the slower takes 80).
Example 3 (fraction of usual speed): Walking at 3/4 of his usual speed, a man is 20 minutes late. Find his usual time.
At 3/4 speed, time becomes 4/3 of usual. Extra time = 1/3 of usual = 20 min, so usual time = 60 minutes.
Shortcut: if speed becomes a/b of usual, usual time = delay × a ÷ (b − a). Here 20 × 3 ÷ 1 = 60. ✔
Average Speed Formula and Tricks for SSC CGL
Average speed = total distance ÷ total time, never the plain average of speeds.
| Case | Formula |
|---|---|
| Two equal distances at x and y | 2xy ÷ (x + y) |
| Three equal distances at x, y, z | 3xyz ÷ (xy + yz + zx) |
| Equal times at x and y | (x + y) ÷ 2 |
Example 4: A man goes to office at 40 km/h and returns at 60 km/h. Find his average speed.
Average = 2 × 40 × 60 ÷ 100 = 48 km/h (not 50).
Example 5: A cyclist covers three equal stretches at 30, 40 and 60 km/h. Find the average speed.
Average = 3 ÷ (1/30 + 1/40 + 1/60) = 3 ÷ (9/120) = 40 km/h.
Late and Early Questions in Speed and Distance
When the same distance is covered at two speeds and the time difference is known:
Distance = (S₁ × S₂ ÷ (S₂ − S₁)) × time difference
Example 6: A student walking at 5 km/h reaches school 7 minutes late. At 6 km/h he is 5 minutes early. Find the distance.
Time difference = 7 + 5 = 12 minutes = 1/5 hour. Distance = (5 × 6 ÷ 1) × 1/5 = 6 km.
Check: 6 km at 5 km/h = 72 min; at 6 km/h = 60 min; difference 12 min. ✔
Relative Speed Formula (Opposite and Same Direction)
| Moving | Relative speed |
|---|---|
| Towards each other (opposite) | S₁ + S₂ |
| Same direction | S₁ − S₂ |
Example 7 (meeting point): Two cars start at the same time from A and B, 300 km apart, towards each other at 40 km/h and 35 km/h. When and where do they meet?
Time = 300 ÷ 75 = 4 hours; distance from A = 40 × 4 = 160 km.
Example 8 (after meeting formula): Two people start from A and B towards each other. After meeting, one takes 9 hours and the other 16 hours to reach their destinations. Find the ratio of their speeds.
S₁ : S₂ = √t₂ : √t₁ = √16 : √9 = 4 : 3.
Example 9 (chase): A thief runs at 10 km/h. A police officer starts chasing 30 minutes later at 12 km/h. When does the officer catch the thief?
Head start = 10 × 0.5 = 5 km. Relative speed = 2 km/h. Time = 5 ÷ 2 = 2.5 hours after the officer starts.
Train Problems Tricks for SSC CGL and Bank Exams
The train must cover its own length + the length of what it crosses.
| Train crosses | Distance to cover | Speed to use |
|---|---|---|
| A pole, tree or standing man | Length of train | Train speed |
| A platform or bridge | Train + platform | Train speed |
| A man walking the same way | Length of train | Train − man |
| A man walking towards it | Length of train | Train + man |
| Another train, opposite direction | Sum of lengths | Sum of speeds |
| Another train, same direction | Sum of lengths | Difference of speeds |
Example 10: A 240 m train passes a pole in 12 seconds. Find its speed in km/h.
Speed = 240 ÷ 12 = 20 m/s = 20 × 18/5 = 72 km/h.
Example 11: A 300 m train at 54 km/h crosses a 150 m platform. How long does it take?
54 km/h = 15 m/s. Time = (300 + 150) ÷ 15 = 30 seconds.
Example 12: Two trains of 150 m and 210 m run at 60 km/h and 48 km/h. How long do they take to cross each other in opposite directions and in the same direction?
- Opposite: relative speed = 108 km/h = 30 m/s. Time = 360 ÷ 30 = 12 s.
- Same direction: relative speed = 12 km/h = 10/3 m/s. Time = 360 ÷ (10/3) = 108 s.
Example 13: A train at 72 km/h passes a man walking at 6 km/h in the same direction in 9 seconds. Find the length of the train.
Relative speed = 66 km/h = 55/3 m/s. Length = 55/3 × 9 = 165 m.
Stoppage Time and Circular Track Questions
Stoppage time per hour = (speed without stops − speed with stops) ÷ speed without stops × 60 minutes.
Example 14: A bus runs at 60 km/h without stops and averages 45 km/h with stops. How many minutes does it stop per hour?
(60 − 45) ÷ 60 × 60 = 15 minutes.
Circular track: first meeting time = track length ÷ relative speed.
Example 15: A and B run on a 600 m circular track at 4 m/s and 6 m/s. When do they first meet if they start together from the same point (a) in opposite directions, (b) in the same direction?
(a) 600 ÷ 10 = 60 s; (b) 600 ÷ 2 = 300 s.
Speed Time and Distance Formulas (Quick Revision Table)
| Situation | Formula |
|---|---|
| km/h → m/s | × 5/18 |
| Average speed, equal distances | 2xy ÷ (x + y) |
| Speed a/b of usual, late by t | Usual time = t × a ÷ (b − a) |
| Late/early at two speeds | D = S₁S₂ ÷ (S₂ − S₁) × time difference |
| After-meeting times t₁, t₂ | S₁ : S₂ = √t₂ : √t₁ |
| Train crossing pole | Time = train length ÷ speed |
| Train crossing platform | Time = (train + platform) ÷ speed |
| Two trains | Sum of lengths ÷ relative speed |
| Stoppage per hour | (S − s) ÷ S × 60 min |
Common Mistakes in Speed Time and Distance Questions
- Averaging speeds directly. 40 and 60 km/h give 48, not 50.
- Mixing units. Convert km/h to m/s before using metres and seconds.
- Forgetting the platform length in train questions.
- Wrong relative speed. Same direction means subtract; opposite means add.
- Ignoring the head start in chase questions.
Speed Time and Distance Questions for SSC CGL (Practice Set with Answers)
- Convert 90 km/h into m/s. Answer: 25 m/s. 90 × 5/18.
- A man goes at 30 km/h and returns at 20 km/h over the same road. Find his average speed. Answer: 24 km/h. 2 × 30 × 20 ÷ 50.
- A train at 54 km/h crosses a pole in 20 seconds. Find its length. Answer: 300 m. 15 m/s × 20.
- A 250 m train at 72 km/h crosses a 350 m bridge. Find the time taken. Answer: 30 s. 600 ÷ 20.
- Two trains of 120 m and 180 m run in opposite directions at 50 km/h and 40 km/h. In how much time will they cross each other? Answer: 12 s. Relative speed 90 km/h = 25 m/s; 300 ÷ 25.
- Walking at 4 km/h a boy is 3 minutes late; at 5 km/h he is 3 minutes early. Find the distance. Answer: 2 km. (4 × 5 ÷ 1) × 6/60.
- A thief runs at 8 km/h. A police officer starts after 1 hour at 10 km/h. In how many hours will the officer catch him? Answer: 4 hours. Head start 8 km; relative speed 2 km/h.
- On a 300 m circular track, A and B run at 5 m/s and 7 m/s. When do they first meet in opposite directions, and in the same direction? Answer: 25 s and 150 s. 300 ÷ 12 and 300 ÷ 2.
- A train at 63 km/h passes a man walking at 9 km/h in the same direction in 16 seconds. Find the length of the train. Answer: 240 m. 54 km/h = 15 m/s; 15 × 16.
- Walking at 4/5 of his usual speed, a man reaches 25 minutes late. Find his usual time. Answer: 100 minutes. 25 × 4 ÷ 1.
For timed practice, take the SSC CGL Time Speed Distance Mock Test 01 and the SSC CHSL Speed Time and Distance Mock Test 01.
Speed Time and Distance FAQs
What is the formula of speed, time and distance?
Distance = Speed × Time. So Speed = Distance ÷ Time and Time = Distance ÷ Speed, with all values in matching units.
How do you convert km/h into m/s?
Multiply by 5/18. To change m/s into km/h, multiply by 18/5. For example, 36 km/h = 10 m/s.
What is the formula of average speed when distances are equal?
For two equal distances at speeds x and y, average speed = 2xy ÷ (x + y). For three equal distances, use 3xyz ÷ (xy + yz + zx).
How do you solve train problems quickly?
Add the lengths of the train and whatever it crosses (zero for a pole), choose the right relative speed (add for opposite, subtract for same direction), convert to m/s and divide.
What is relative speed?
It is the speed of one object as seen from another. Objects moving towards each other have relative speed S₁ + S₂; objects moving in the same direction have S₁ − S₂.
How many speed time and distance questions come in SSC CGL?
Usually 1 to 2 in SSC CGL Tier 1, sometimes as a train question. SSC CHSL and bank Clerk exams also ask 1 to 2, often as arithmetic word problems.
Practice Next
- Mock tests: SSC CGL Time Speed Distance Mock Test 01, SSC CHSL Speed Time and Distance Mock Test 01, SSC CGL Maths Mini Mock Test 03 and IBPS Clerk Quant Mini Mock Test 04.
- Related notes: boats and streams tricks for bank exams, time and work tricks for SSC CGL, ratio and proportion for SSC CGL and LCM and HCF tricks for SSC CGL.
- Exam details: SSC CGL 2026 and SSC CHSL 2026.
- Browse all study notes.