Time – Speed – Distance (T‑S‑D)
Quick cheat‑sheet for SSC‑JE Quantitative Aptitude
(All explanations are in plain English – no hard maths terms!)
📖 Table of Contents
- What is it?
- The basic rule
- How to use the rule
- Common twists
- Mini‑examples
- Tips for the exam
- Practice problems
1. What is it?
- Distance = How far you travel (e.g., 100 km).
- Speed = How fast you travel (e.g., 50 km per hour).
- Time = How long you travel (e.g., 2 hours).
Think of a road trip:
- Distance is the length of the road.
- Speed is how fast you drive.
- Time is how many hours you spend driving.
2. The basic rule
Distance = Speed × Time
(In words: “How far you go equals how fast you go times how long you go.”)
- Speed is usually given in km/h, m/s, etc.
- Time is in hours, minutes, or seconds – convert if necessary.
- Distance comes out in the same unit as the speed’s unit × time’s unit.
No fancy symbols – just multiply speed by time.
3. How to use the rule
| Want to find | What you need | What you compute |
|---|---|---|
| Distance | Speed & Time | Speed × Time |
| Speed | Distance & Time | Distance ÷ Time |
| Time | Distance & Speed | Distance ÷ Speed |
Remember:
- Division is “take one part of the whole.”
- Multiplication is “put them together.”
4. Common twists
| Twist | What it means | Quick trick |
|---|---|---|
| Average speed | Total distance ÷ total time | Same rule, but use total values |
| Relative speed | How fast two objects move together or apart | Add or subtract speeds |
| Change of speed | Speed changes at a point | Split the trip into parts, solve each part, add distances or times |
| Speed in m/s | Speed given in meters per second | Convert to km/h if distance is in km (×3.6) or convert distance to meters |
5. Mini‑examples
Example 1 – Find Distance
A car drives at 60 km/h for 3 hours.
Distance = 60 × 3 = 180 km.
Example 2 – Find Speed
A train covers 150 km in 2.5 hours.
Speed = 150 ÷ 2.5 = 60 km/h.
Example 3 – Find Time
A bike travels 80 km at 20 km/h.
Time = 80 ÷ 20 = 4 hours.
6. Tips for the exam
| Tip | Why it helps |
|---|---|
| Always check units | Mixing km and m leads to wrong answers. |
| Convert minutes to hours | 30 min = 0.5 h. |
| Use “divide” when you see “÷” | Speed ÷ Time = Distance. |
| Break long problems into parts | Easier to keep numbers straight. |
| Quick mental math | 60 × 0.5 = 30; 120 ÷ 30 = 4. |
| Read the question twice | Make sure you know what is asked. |
7. Practice problems
Try solving. Check your answer after each one.
- Time – A cyclist covers 45 km at 15 km/h.
- Speed – A bus travels 180 km in 4 hours.
- Distance – A plane flies for 2.5 hours at 480 km/h.
- Relative speed – Two cars start from the same point, one goes 60 km/h and the other 80 km/h. How far apart are they after 1.5 hours?
- Change of speed – A runner covers 4 km in 20 min at 12 km/h. After that, he runs the next 6 km at 18 km/h. Total time?
Answers
- 3 hours
- 45 km/h
- 1200 km
- 30 km
- 25 minutes
✅ Bottom line:
Just remember the simple rule – Distance = Speed × Time – and you can answer any Time‑Speed‑Distance question in a flash. Happy studying!