📚 Lakshadweep TET – Quantitative Aptitude
Topic: Bar & Pie Charts
Objective – Understand how to read, interpret, and perform basic calculations with bar and pie charts, the most common data‑representation tools in the TET exam.
1️⃣ Simple Explanation
| Chart | What it shows | Typical use in TET |
|---|---|---|
| Bar Chart | Quantitative data distributed among categories (e.g., number of students in each class, sales of products). Bars may be vertical or horizontal. | Comparing counts, finding the maximum/minimum, computing percentages. |
| Pie Chart | Parts of a whole expressed as angles or wedges. Each wedge’s size is proportional to the part’s value. | Showing proportions, percentages, or ratios of a whole (e.g., distribution of votes, budget allocation). |
Key Idea:
Bar charts are great for exact counts and comparisons.
Pie charts are ideal for percentage/ratio representation.
2️⃣ Key Points to Remember
| Aspect | Bar Charts | Pie Charts |
|---|---|---|
| Axis | Horizontal (categories) & Vertical (value scale). Scale must be uniform. | No axis – whole is 360° (or 100%). |
| Units | Often given in numbers, thousands, etc. | Often given in percentages or parts of 100. |
| Reading | 1. Identify categories. 2. Read bar height (or length). 3. Use scale to convert to actual value. | 1. Identify wedges. 2. Read angle or percentage. 3. Convert to part of whole. |
| Common Tasks | • Find total of all bars. • Find percentage of a particular bar. • Compare two bars. |
• Find percentage of a wedge. • Find missing percentage if one wedge is omitted. • Find ratio of two wedges. |
| Formula | Percentage = (Bar Value / Total Value) × 100 |
Same as bar chart – Part % = (Part / Whole) × 100 |
| Important Checks | • Ensure bars don’t cross each other. • Check that the scale is correctly labeled. |
• Sum of all percentages should be 100 (or 360°). • Wedges should be proportional. |
| Common Mistakes | • Misreading the scale (e.g., 10 units = 100). • Forgetting to add all bars before computing percentages. |
• Adding angles instead of converting to percentages. • Assuming missing wedge is zero. |
3️⃣ Worked Example
3.1 Bar Chart Example
Problem
A bar chart shows the number of students in five classes A–E:
| Class | Students |
|---|---|
| A | 48 |
| B | 32 |
| C | 56 |
| D | 24 |
| E | 40 |
Questions
- What is the total number of students?
- Which class has the highest enrollment?
- What percentage of the total does Class C represent?
Solution
| Step | Calculation | Result |
|---|---|---|
| 1. Total | 48 + 32 + 56 + 24 + 40 | 200 |
| 2. Highest | Compare: 56 (Class C) is largest | Class C |
| 3. Percentage of C | (56 ÷ 200) × 100 | 28 % |
Answer
- Total students = 200.
- Highest enrollment = Class C.
- Class C represents 28 % of all students.
3.2 Pie Chart Example
Problem
A pie chart shows the distribution of national budget (in ₹ crore) for 2025:
| Category | Percentage |
|---|---|
| Education | 25 % |
| Health | 15 % |
| Infrastructure | 35 % |
| Others | ? |
Question
What percentage is allocated to “Others”?
Solution
Sum of given percentages = 25 + 15 + 35 = 75 %.
Missing percentage = 100 % – 75 % = 25 %.
Answer
Others = 25 % of the national budget.
3.3 Combined Question (Bar + Pie)
Problem
A bar chart lists the number of books sold by a school library in 6 months:
Jan–30, Feb–45, Mar–40, Apr–50, May–35, Jun–55.
The total books sold in the semester are shown in a pie chart as 300 books (the whole).
Questions
- Verify the total using the bar chart.
- What percentage of the total was sold in May?
- In the pie chart, what wedge angle (in degrees) represents books sold in April?
Solution
| Step | Calculation | Result |
|---|---|---|
| 1. Total (bar) | 30 + 45 + 40 + 50 + 35 + 55 = 255 | 255 |
| Note: The pie chart says 300 → inconsistency; exam may provide correct values; assume 300 is the given whole. | ||
| 2. May % | (35 ÷ 300) × 100 = 11.67 % | ≈ 11.7 % |
| 3. April wedge | 50 books → (50 ÷ 300) × 360° = (1/6) × 360° = 60° |
Answers
- Bar total = 255.