Handling Data 6
3 marks · NormalA grouped frequency table shows the heights (in cm) of a sample of plants:
| Height (cm) | Frequency |
|---|---|
| 0 < h \leq 10 | 4 |
| 10 < h \leq 20 | 10 |
| 20 < h \leq 40 | 12 |
Work out the frequency density for each group.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
0 < h ≤ 10: 0.4; 10 < h ≤ 20: 1.0; 20 < h ≤ 40: 0.6 (±0.01)
Common mistakes: Using wrong class width; Confusing frequency with frequency density
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Writes frequency density formula: frequency ÷ class width.
A1 · 1 mark · Calculates all class widths correctly (10, 10, 20).
A2 · 1 mark · Gives all three correct frequency densities: 0.4, 1.0, and 0.6.
Worked solution
Frequency density = frequency ÷ class width.
Class widths: 0 < h ≤ 10: width = 10; 10 < h ≤ 20: width = 10; 20 < h ≤ 40: width = 20.
Frequency densities: 4/10 = 0.4; 10/10 = 1.0; 12/20 = 0.6.