Time‑Speed‑Distance (TSD) – Delhi TET Quantitative Aptitude
(Easy, beginner‑friendly notes for quick revision)
1. The Everyday Idea
- Speed – how fast you go.
Analogy: How many miles you cover in one hour driving a car. - Distance – how far you travel.
Analogy: The stretch of road between your home and the grocery store. - Time – how long it takes.
Analogy: Minutes it takes to walk from the bus stop to the school.
If you know any two of these, you can find the third.
2. Simple Formulas
| What you want | Formula (plain words) | Example numbers |
|---|---|---|
| Distance | Speed × Time | 30 km/h × 2 h = 60 km |
| Speed | Distance ÷ Time | 60 km ÷ 2 h = 30 km/h |
| Time | Distance ÷ Speed | 60 km ÷ 30 km/h = 2 h |
Keep units the same (km with km/h, minutes with km/min, etc.).
3. Step‑by‑Step Solving
- Read the question carefully – find the two known values.
- Choose the right formula – decide which one gives the missing value.
- Insert the numbers – watch the units.
- Do the arithmetic – remember division is the same as “÷”.
- Check the answer – does it make sense? (e.g., time can’t be negative).
4. Tiny Example
Problem
A train travels 120 km in 3 hours.
What is its speed?
Solution
- Known: Distance = 120 km, Time = 3 h.
- Missing: Speed.
- Formula: Speed = Distance ÷ Time.
- Compute: 120 ÷ 3 = 40 km/h.
- Check: 40 km/h × 3 h = 120 km ✔️
5. Quick Practice Problems
| # | Question | Answer | How to get it |
|---|---|---|---|
| 1 | A bike covers 15 km in 1 h 30 min. Speed? | 10 km/h | Convert 1 h 30 min = 1.5 h → 15 ÷ 1.5 |
| 2 | A car travels at 50 km/h. Distance in 2 h? | 100 km | 50 × 2 |
| 3 | A bus needs 4 h to reach the city 200 km away. Speed? | 50 km/h | 200 ÷ 4 |
6. Tips for Delhi TET
- Keep a small table of the three formulas for quick reference.
- Always write units to avoid unit‑mix mistakes.
- Round only at the end – keep intermediate numbers exact.
- Think of the problem as a story – it helps to decide which formula to use.
7. Summary
- Speed = distance ÷ time
- Distance = speed × time
- Time = distance ÷ speed
Use the two known values, pick the right formula, plug in, and get the answer. Simple, fast, and fool‑proof for the TET exam. Happy studying!