Pie Charts and Line Graphs

Pie charts

A pie chart shows how a total (100% or 360°) is divided.

• 100% = 360°, so 1% = 3.6°.
• Degrees → %: (angle/360) × 100. 72° = 20%.
• % → degrees: % × 3.6. 15% = 54°.
• Value of a sector = % × Total. Rent 25% of ₹40,000 = ₹10,000.

Line graphs

A line graph shows change over time. The steeper the line, the larger the change.

Example: temperature Mon 20°, Tue 24°, Wed 18°, Thu 26°. Changes: +4, −6, +8 → greatest rise is Wed → Thu.

Solving strategy

1. Note the total (for pie charts) and the scale (for line graphs).
2. Compare sectors or slopes visually before calculating.
3. Use percentages directly instead of converting everything to values.

Exam tips (RRB NTPC)

1. Sectors in a pie chart always add up to 360° / 100%.
2. For "maximum increase" read the differences, not the highest point.

Analogy

A pie chart is like sharing one pizza among friends. However many slices there are, together they always make one whole pizza (360°). A line graph is like your phone's battery history — you care about where the line drops or rises sharply, not just its highest point.