Data interpretation and graphical representation

Key Points at a Glance

1. 1

   Syllabus boundary: for CET Senior Secondary, keep this topic to graphical representation of data, average, percentage, ratio-proportion, and basic comparison; do not treat mean-median-mode as a separate statistics chapter.

2. 2

   Graph questions start with reading the title, unit, scale, category labels, and time period; wrong answers often come from reading the wrong axis or ignoring the unit.

3. 3

   Bar charts compare categories; line graphs show change over time; pie charts show parts of a whole; tables may require totals, differences, averages, ratios, or percentages.

4. 4

   Percentage share = part / total x 100; percentage change = change / original value x 100; percentage-point change is the direct difference between two percentages.

5. 5

   Average = sum of observations / number of observations; for combined groups, use total sum / total count, not the simple average of two averages unless the group sizes are equal.

6. 6

   Ratio compares quantities in the same unit; before simplifying a ratio, convert both terms to the same unit and keep the order asked in the question.

7. 7

   Pie chart method: sector value = sector angle / 360 x total; sector angle = sector value / total x 360; equal angles mean equal values only when totals are equal.

8. 8

   Exam method: read, mark required entries, choose the formula, calculate, check units, and compare with the option size before filling the OMR.