Study Material — 1 PYQs (2018–2018) · Concept Notes · Shortcuts
NDA Line Graphs is a frequently tested subtopic — 1 previous year questions from 2018–2018 papers are included below with concept notes, key rules and shortcut tricks.
Line graphs are one of the most frequently tested data interpretation questions in SSC CGL. They show how data changes over time using connected points on a coordinate plane. The x-axis typically shows time periods (years, months, days) while the y-axis shows values (sales, population, temperature, etc.).
Key Rules for Line Graphs:
1.
Each point represents a specific value at a specific time
2. The line connecting points shows the trend between periods
3. Steep upward slope = rapid increase
4.
Steep downward slope = rapid decrease
5. Horizontal line = no change
6. Multiple lines can represent different categories for comparison
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Formula Block
Memorise — at least one formula appears in every paper
• Percentage Change = [(New Value - Old Value) / Old Value] × 100
• Average = Sum of all values / Number of values
• Rate of Change = (Change in Value) / (Change in Time)
• Ratio = Value A : Value B
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Exam Patterns
What examiners ask — read before attempting PYQs
→Common question types include
percentage increase/decrease between years, finding averages, comparing values, calculating ratios, and identifying maximum/minimum values. Questions often test your ability to read coordinates accurately and perform quick calculations.
Shortcut Trick #1 - Quick Percentage Change:
For small percentages, use this mental math trick: 10% = 1/10, 20% = 1/5, 25% = 1/4, 33.33% = 1/3, 50% = 1/2. This helps you estimate answers quickly without lengthy calculations
Answer - 40% decrease
Worked Example 2:
From the same graph, find the average sales over three years.
1
Add all values - 40 + 50 + 30 = 120 lakhs
2
Divide by number of years - 120 ÷ 3 = 40 lakhs
3
Answer - Average sales = 40 lakhs
Shortcut Trick #2 - Reading Values Quickly:
Always check the scale first. If y-axis shows 'in thousands' or 'in lakhs', multiply accordingly. Mark the grid lines mentally to avoid misreading coordinates.
Shortcut Trick #3 - Estimation for Speed:
For percentage calculations, round numbers to nearest 10 or 5 for quick estimation. Then fine-tune if needed. This saves precious exam time.
The #1 Most Common Trap:
Students often misread the scale or units on axes. A graph showing 'Sales in thousands' means 5 on the graph = 5,000 actual sales. Always check what the axes represent before solving. This single mistake causes more wrong answers than calculation errors. Another trap is confusing percentage increase with percentage of total - read questions carefully to understand what exactly is being asked.
Key Points to Remember
Line graphs show data changes over time using connected points on coordinate axes