DepEd MELC reviewer for Grade 10 Mathematics, Quarter 4. Study the rules, worked formulas, and exam hacks below.
1
Quartiles, Deciles, Percentiles
| Measure | Divides data into |
|---|---|
| Quartiles (Q1–Q3) | 4 equal parts |
| Deciles (D1–D9) | 10 equal parts |
| Percentiles (P1–P99) | 100 equal parts |
💡 Exam Hack
The median = Q2 = D5 = P50 — they all mark the middle (50%).
2
Interquartile Range
IQR = Q3 − Q1
IQR measures the spread of the middle 50% and helps detect outliers.
3
Interpreting Position
A score at the 90th percentile means it is higher than 90% of the data.
⚠️ Common Mistake
The 90th percentile does NOT mean a score of 90 — it means better than 90% of scores.
4
Worked Example
Data: 2, 4, 6, 8, 10, 12, 14, 16. Find Q1 and Q3.
Q1 = 5 (avg of 4 & 6) · Q3 = 13 (avg of 12 & 14) · IQR = 8
📌 Quick Recap — Master These
Before your test, make sure you can confidently do each of the following:
- Explain and apply Quartiles, Deciles, Percentiles.
- Explain and apply Interquartile Range.
- Explain and apply Interpreting Position.
- Explain and apply Worked Example.
Re-read any section above where you hesitate, then try the worked example again without looking.