Line Graph Data Interpretation: The Short Answer
A line graph plots values as points joined by straight lines, usually over years or months. In bank exams a line graph DI set gives one or two lines and asks for totals, averages, differences, ratios, percentages and percentage change. Most questions are answered with two formulas: percentage change = (new − old) ÷ old × 100 and A as a percentage of B = A ÷ B × 100. The key trick is that the steepest upward segment is not always the highest percentage increase, because percentage change depends on the starting value too.
Key takeaway for bank exams: IBPS PO, SBI PO and RRB PO prelims usually carry one DI set of 5 questions, and line graphs (single, double or percentage-type) are one of the four common formats with bar graphs, pie charts and tables. SBI Clerk and IBPS Clerk mains also set line graph DI. Every answer in this note was computed in Python.
Line graph questions are mostly percentage work, so revise the percentage tricks for SSC CGL first, and compare this format with the bar graph data interpretation and pie chart data interpretation notes.
Types of Line Graph DI for Bank Exams
| Type | What the lines show | What usually gets asked |
|---|---|---|
| Single line graph | One quantity over time (production, sales) | Percentage change, average, highest or lowest year |
| Double or multiple line graph | Two or more companies or items over the same years | Difference, ratio, combined total, which grew more |
| Percentage line graph | Profit %, growth % or share % each year | Income from expenditure, expenditure from income |
| Line graph with a table | Line gives one variable, table gives another | Combined calculation across both sources |
| Cumulative line graph | Running total up to each point | Value for one year = this point − previous point |
The percentage-type graph is the one students lose marks on, because the line shows a rate, not an amount. If the graph shows profit %, you cannot compare profit amounts of two years without the expenditure or income.
Line Graph DI Formulas (Quick Table)
| What is asked | Formula |
|---|---|
| Percentage change from year 1 to year 2 | (Year 2 − Year 1) ÷ Year 1 × 100 |
| A as a percentage of B | A ÷ B × 100 |
| A is what percent more than B | (A − B) ÷ B × 100 |
| Average over n years | Sum of the n values ÷ n |
| Ratio | Write both totals, cancel the HCF |
| Profit % | (Income − Expenditure) ÷ Expenditure × 100 |
| Income from profit % | Expenditure × (100 + profit %) ÷ 100 |
| Expenditure from profit % | Income × 100 ÷ (100 + profit %) |
Line Graph Data Interpretation Questions (Solved Set)
Directions: The line graph shows the production (in thousand units) of two companies, A and B, from 2020 to 2025. Because the graph image is not printed here, the points are given in the table exactly as you would read them off the graph.
| Year | Company A | Company B |
|---|---|---|
| 2020 | 240 | 200 |
| 2021 | 300 | 250 |
| 2022 | 270 | 300 |
| 2023 | 360 | 280 |
| 2024 | 315 | 336 |
| 2025 | 430 | 385 |
Q1. What is the percentage increase in the production of company A from 2020 to 2021? (300 − 240) ÷ 240 × 100 = 60 ÷ 240 × 100 = 25%.
Q2. In which year did company A show the highest percentage increase over the previous year? Year-on-year changes for A: 2021 +25%, 2022 −10%, 2023 +33.33%, 2024 −12.5%, 2025 +36.51%. The answer is 2025 (115 ÷ 315 × 100 ≈ 36.51%). Notice that 2022 to 2023 (+90) and 2024 to 2025 (+115) both look steep on the graph; only the calculation separates them.
Q3. What is the ratio of the total production of A in 2021 and 2022 together to that of B in the same two years? A = 300 + 270 = 570; B = 250 + 300 = 550. Ratio = 570 : 550 = 57 : 55.
Q4. Production of A in 2023 is what percentage of production of B in 2023? 360 ÷ 280 × 100 = 128.57% (about 128 4/7 %).
Q5. What is the average production of company A from 2021 to 2023? (300 + 270 + 360) ÷ 3 = 930 ÷ 3 = 310 thousand units.
Q6. By what percentage did the production of B rise from 2020 to 2025? (385 − 200) ÷ 200 × 100 = 92.5%.
Q7. In how many years was the production of B more than that of A? B > A in 2022 (300 > 270) and 2024 (336 > 315). Answer: 2 years.
Q8. In which year was the combined production of A and B the highest, and what was it? Combined: 440, 550, 570, 640, 651, 815. Highest is 2025 with 815 thousand units.
Percentage Line Graph Questions (Profit Percent Type)
Directions: The line graph shows the profit percentage of company P from 2021 to 2025: 2021 – 20%, 2022 – 25%, 2023 – 30%, 2024 – 15%, 2025 – 40%. Profit % = (Income − Expenditure) ÷ Expenditure × 100.
Q1. If the expenditure of P in 2024 was ₹80 lakh, what was its income? Income = 80 × 115 ÷ 100 = ₹92 lakh.
Q2. If the income of P in 2025 was ₹98 lakh, what was its expenditure? Expenditure = 98 × 100 ÷ 140 = ₹70 lakh.
Q3. If the expenditure of P was the same in 2022 and 2023, what is the ratio of income in 2022 to income in 2023? Income is proportional to (100 + profit %): 125 : 130 = 25 : 26.
Q4. If the income in 2021 was ₹60 lakh, what was the profit? Expenditure = 60 × 100 ÷ 120 = 50, so profit = 60 − 50 = ₹10 lakh.
Trap: "Profit was highest in 2025" is not a valid conclusion from a profit % graph alone. A company with a lower profit % on a much bigger expenditure can earn more. Always look for the base (income or expenditure) before comparing amounts.
Line Graph DI Tricks for SBI Clerk, IBPS Clerk and SBI PO
- Make the table first. Read every point once and write it down. Re-reading the graph for every question wastes time and causes misreads.
- Check the unit and the scale. Thousand units, lakh, crore, or %? Does the axis start at zero? A graph whose y-axis starts at 200 makes small changes look huge.
- Use fraction equivalents. 25% = 1/4, 33.33% = 1/3, 12.5% = 1/8, 16.67% = 1/6, 37.5% = 3/8. A change of 60 on a base of 240 is 1/4, so 25% at a glance.
- Compare growth by ratio, not by gap. To find the highest percentage increase, compare new ÷ old. 430 ÷ 315 ≈ 1.365 beats 360 ÷ 270 ≈ 1.333.
- Answer "how many years" questions by scanning, not computing. Count the points where one line is above the other.
- For averages, use the deviation method. For 300, 270, 360 take 300 as the base: deviations 0, −30, +60 sum to +30, so average = 300 + 30 ÷ 3 = 310.
- Approximate when options are far apart. In SBI PO and IBPS PO prelims, if the options differ by more than 5%, round values to the nearest 5 or 10 and pick the closest option.
- For a cumulative graph, subtract. The value for a year is the cumulative point minus the previous cumulative point.
Line Graph vs Bar Graph vs Pie Chart in DI
| Feature | Line graph | Bar graph | Pie chart |
|---|---|---|---|
| Best for | Trends over time | Comparing categories | Share of a whole |
| Typical question | Percentage change, highest growth | Totals, differences | Central angle, share value |
| Common trap | Steep line ≠ highest percentage | Stacked bar segments | Angle vs percentage confusion |
| Speed tip | Note the y-axis start | Read all bars into a table | 1% = 3.6° |
Common Mistakes in Line Graph Questions
- Using the new value as the base for percentage change. The base is always the earlier year.
- Mixing up "A is what % of B" and "A is what % more than B". For A = 360, B = 280 the first is 128.57% and the second is 28.57%.
- Reading a profit % line as profit amount.
- Ignoring a y-axis that does not start at zero.
- Rounding too early. Keep two decimals until the last step, then match the options.
- Missing the legend in a double line graph and swapping the two companies.
Line Graph DI Practice Questions (with Answers)
Use the production table of companies A and B above.
1. What is the percentage decrease in A's production from 2023 to 2024? (360 − 315) ÷ 360 × 100 = 12.5%.
2. What is the total production of B over all six years? 200 + 250 + 300 + 280 + 336 + 385 = 1,751 thousand units.
3. What is the difference between the total production of A and B over the six years? A total = 1,915; B total = 1,751; difference = 164 thousand units.
4. In which year did B record the highest percentage increase over the previous year? B changes: 2021 +25%, 2022 +20%, 2023 −6.67%, 2024 +20%, 2025 +14.58%. Answer: 2021.
5. A's production in 2024 is what percent of the combined production of A and B in 2024? 315 ÷ 651 × 100 ≈ 48.39%.
6. In which year was the gap between A and B the largest? Gaps (A − B): 40, 50, −30, 80, −21, 45. Largest is 2023 (80 thousand units).
7. By what percentage did the combined production of A and B rise from 2020 to 2025? (815 − 440) ÷ 440 × 100 ≈ 85.23%.
8. In how many years was A's production above its own six-year average? Average = 1,915 ÷ 6 ≈ 319.17. Years above it: 2023 (360) and 2025 (430). Answer: 2 years.
9. What is the average production of B from 2023 to 2025? (280 + 336 + 385) ÷ 3 = 1,001 ÷ 3 ≈ 333.67 thousand units.
10. Using the profit % graph of P, if expenditure in 2023 was ₹50 lakh, what was the income? 50 × 130 ÷ 100 = ₹65 lakh.
Line Graph DI Questions in IBPS PO, SBI PO and Clerk: What to Expect
| Exam | Where line graph DI appears | Typical size |
|---|---|---|
| IBPS PO and SBI PO prelims | Quantitative Aptitude section | One DI set of 5 questions (line, bar, pie, table or caselet) |
| IBPS PO and SBI PO mains | Data Analysis and Interpretation | Several sets, often mixed graph + table |
| IBPS Clerk and SBI Clerk prelims | Numerical Ability | Occasional set; arithmetic and simplification dominate |
| IBPS Clerk and SBI Clerk mains | Quantitative Aptitude | One or two DI sets, line and bar are common |
| SSC CGL Tier 2 | Mathematical Abilities | Full DI sets on bar, line and pie |
The exact mix changes every year, so treat this as a guide to how often you will meet the format, not a fixed rule.
Line Graph Data Interpretation FAQs
How do you solve line graph DI questions quickly?
Write every point into a small table first, check the unit and the starting value of the y-axis, then use fraction equivalents for percentages. Compare growth with the ratio new ÷ old instead of the size of the jump.
What is the formula for percentage change in a line graph?
Percentage change = (new value − old value) ÷ old value × 100. The old (earlier) value is always the base.
Is the steepest line segment the highest percentage increase?
Not always. The slope shows the absolute change. A smaller jump from a small base can be a bigger percentage than a larger jump from a big base, so calculate new ÷ old for each candidate.
How do you find income from a profit percentage line graph?
Income = Expenditure × (100 + profit %) ÷ 100, and Expenditure = Income × 100 ÷ (100 + profit %). You need at least one amount; the graph alone only gives the rate.
Are line graph questions asked in SBI Clerk and IBPS Clerk?
Yes. They are more common in clerk mains and in PO prelims and mains, but clerk prelims can also carry a short DI set.
What is the difference between a line graph and a bar graph in DI?
A line graph highlights a trend over time and is best for growth questions; a bar graph highlights comparison between categories. The calculations (percentage, ratio, average) are the same for both.
Practice Next
- Mock tests: SBI Clerk Data Interpretation Practice Test 01, IBPS Clerk Data Interpretation Practice Test 02, SBI PO Data Interpretation Practice Test 01 and IBPS PO Data Interpretation Practice Test 01.
- Related notes: bar graph data interpretation for bank exams, pie chart data interpretation for bank exams, caselet DI for SBI Clerk and percentage tricks for SSC CGL.
- Exam details: SBI Clerk 2026 notification.
- Browse all study notes.