PET 2026 · CSAT

Pie charts: angle, share and count

Convert between 360° angles, 100% shares and actual counts across single or dual pie charts

MINDMAPS FOR UPSCPET 2026 · VISUAL REVISION

Pie charts: angle, share and count

Convert between 360° angles, 100% shares and actual counts across single or dual pie charts

Pie Chart Conversions
A quarter of a circle90°One full circle = 360°90 ÷ 360 = 1/425% of the totalIf N = 200, the sector represents 50
A quarter of a circleSwipe sideways to explore the diagram.

Angle, Percentage and Count

  • One complete circle represents 360° or 100% of the total population N.
  • Sector count = N × (θ / 360°) = N × (p / 100); 1% of the circle equals 3.6°.
  • For N = 1200, Bus (150°) + Car (45°) = 195°, giving 1200 × 195/360 = 650 students.

Ratios Within a Single Pie

  • Within the same pie chart, the total N cancels out in any ratio or fraction between sectors.
  • Bus + Car (195°) to Motorcycle + Bicycle (165°) simplifies directly as 195 : 165 = 13 : 11.
  • Motorcycle + Bicycle as a fraction of the whole is simply 165° / 360° = 11/24.

Comparing Across Two Pie Charts

  • Across two pies with different totals N₁ and N₂, never compare percentages without their totals.
  • Reduce the ratio of totals first: 24,700 : 27,300 divides by 1,300 to give 19 : 21.
  • In Institute S, PG (21% of 24,700) to Grad (14% of 27,300) is (19 × 21) : (21 × 14) = 19 : 14.

Internal Switch vs New Entrants

  • A switch between sectors keeps N fixed: 50 students out of 1200 equals (50/1200) × 360° = 15°.
  • When 50 Car users switch to Bicycle (75°), the new Bicycle angle is 75° + 15° = 90°.
  • New entrants change the total: (500 + 300)/(1200 + 300) = 8/15 = 53⅓%.
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