Data Representation and Interpretation — O/L Mathematics

What must I remember about Data Representation and Interpretation?

• Cumulative frequency is the running total of frequencies up to the upper boundary of each class interval.
• Cumulative frequency curve (Ogive): Plotted using upper class boundaries on the horizontal axis and cumulative frequencies on the vertical axis, joined by an S-shaped smooth curve.
• Median (Q₂): The 50th percentile value corresponding to (N / 2) on the cumulative frequency axis.
• Quartiles and Interquartile Range: Lower quartile (Q₁) at (N / 4); Upper quartile (Q₃) at (3N / 4); Interquartile Range (IQR) = Q₃ - Q₁.
• Box-and-whisker plot: Displays the five-number summary (Minimum, Q₁, Median Q₂, Q₃, Maximum) along a number scale.

Test yourself (1 minute)

1. Upper boundary plotting rule

   Always plot cumulative frequency against UPPER class boundaries, NEVER against class mid-values.

2. Start at zero frequency

   The ogive curve must start on the horizontal axis at the lower boundary of the very first class interval (cumulative frequency = 0).

3. Reading percentiles accurately

   Show dashed projection lines from the vertical axis to the curve and down to the horizontal axis to secure method marks.

Practise Data Representation and Interpretation questions today

Source: NIE G.C.E. (O/L) Mathematics Syllabus (Grade 11, Unit 15)

What should I study first?

What comes next?

Next in the syllabus

Where does Data Representation and Interpretation fit in the syllabus?

Grade 11 · Term 2