Maths Dictionary · SS 2
Cumulative frequency
Simple meaning
A running total of the frequencies. Its graph is an ogive.
Example
Frequencies 3, 5, 2 give cumulative frequencies 3, 8, 10.
See it
From the Cumulative Frequency lesson. Try moving things around.
Cumulative freq.20
About 20 of the 40 scored 30.5 or less.
Median
≈ 30.5
at n/2 = 20
Q₁
≈ 19.2
at n/4 = 10
Q₃
≈ 38.7
at 3n/4 = 30
IQR
≈ 19.4
Q₃ − Q₁
| Marks | f | Upper bound. | Cum. freq. |
|---|---|---|---|
| 1–10 | 4 | 10.5 | 4 |
| 11–20 | 7 | 20.5 | 4 + 7 = 11 |
| 21–30 | 9 | 30.5 | 11 + 9 = 20 |
| 31–40 | 12 | 40.5 | 20 + 12 = 32 |
| 41–50 | 8 | 50.5 | 32 + 8 = 40 |