Practice Questions
Concept Explanation
Line graphs show change over time by connecting data points. The slope between points indicates rise or fall.
How to Read Line Graphs
- Read values at each marked point on the time axis.
- Steeper upward slope = faster increase.
- A flat segment means no change.
Calculation Shortcuts
- Absolute change = later value − earlier value.
- % change = (change ÷ original) × 100.
- Average over period = sum of values ÷ number of periods.
Example
Points: Year 2020 = 120, 2021 = 150. Increase = 30; % increase = (30/120) × 100 = 25%.
Common Trap
Do not assume linear growth continues beyond the last point unless the question states it.
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Q1 Easy
A line graph shows Year 2020 = 120, 2021 = 150. Absolute increase is:
Explanation150 − 120 = 30. -
Q2 Medium
Year 2020 = 120, 2021 = 150. Percentage increase is:
Explanation(30/120) × 100 = 25%. -
Q3 Easy
Monthly points: Jan = 80, Feb = 100, Mar = 90. Total for three months is:
Explanation80 + 100 + 90 = 270. -
Q4 Easy
A line falls from 200 to 160. Absolute decrease is:
Explanation200 − 160 = 40. -
Q5 Medium
Value drops from 200 to 160. Percentage decrease is:
Explanation(40/200) × 100 = 20%. -
Q6 Easy
Points Q1 = 100, Q2 = 130, Q3 = 110, Q4 = 160. Highest value is in:
ExplanationQ4 = 160 is the maximum. -
Q7 Easy
Five readings: 50, 60, 70, 80, 90. Average is:
Explanation350/5 = 70.
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Q8 Medium
2018 = 180, 2019 = 216. Percentage increase is:
Explanation(36/180) × 100 = 20%. -
Q9 Medium
From Month 1 = 90 to Month 2 = 108, the increase is what % of Month 1?
Explanation(18/90) × 100 = 20%. -
Q10 Easy
Readings: 120, 120, 120 for three months. The trend is:
ExplanationAll three values are equal. -
Q11 Hard
2017 = 250, 2018 = 300, 2019 = 360. Each year shows the same percentage increase. That rate is:
Explanation250 to 300: +20%; 300 to 360: +20%. -
Q12 Medium
Peak = 240 at Jul; trough = 160 at Jan on the same line graph. Difference is:
Explanation240 − 160 = 80. -
Q13 Easy
Week 1 = 45, Week 2 = 54, Week 3 = 48. Week 2 exceeds Week 1 by:
Explanation54 − 45 = 9. -
Q14 Hard
Half-year totals from two lines: Line A sum = 420, Line B sum = 480. Line B exceeds Line A by:
Explanation480 − 420 = 60.
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DS1 Medium
What is the percentage increase from 2020 to 2021?
Statement I2020 = 120 and 2021 = 150.
Statement IIThe absolute increase is 30.
ExplanationNeed original and new value: (30/120) × 100 = 25%. -
DS2 Easy
What is the average of three monthly readings?
Statement IValues are 80, 100 and 90.
Statement IITheir sum is 270.
ExplanationStatement I alone: average = 90.
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DS3 Medium
What is the percentage decrease from 200 to 160?
Statement IThe value fell by 40.
Statement IIThe final value is 160.
ExplanationNeed both start (200) and end (160): (40/200) × 100 = 20%. -
DS4 Easy
What is the highest quarterly value?
Statement IQ1 = 100, Q2 = 130, Q3 = 110, Q4 = 160.
Statement IIQ4 is 30 more than Q1.
ExplanationStatement I alone: highest is Q4 = 160.