Reading & Calculating from Data Tables

🎯 Learning Objective

Read rows and columns of a table and quickly find totals, averages, ratios and 'which is highest' answers.

💡 Concept

• A table shows data in rows and columns — read the row and column headings FIRST
• Row total = add across a row; Column total = add down a column
• Average of a row/column = its total ÷ number of entries
• 'Which year/company is highest?' → compare the required totals, do not eyeball
• Ratio and percentage questions use the same basic formulas — the table only supplies the numbers

🧮 Key Formulas

Average = Total ÷ Number of entries

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Percentage share = (Part ÷ Whole) × 100

✏️ Easy Example

Q. A table shows sales (in ₹ crore) of 4 companies A, B, C, D over 3 years. A = 120, 150, 180; B = 200, 180, 220; C = 90, 140, 160; D = 160, 200, 240 (for 2021, 2022, 2023). Find the total sales of company D over the 3 years.

1. Read D's row: 160, 200, 240
2. Total = 160 + 200 + 240

Answer: ₹600 crore

🇮🇳 Real-Life Example

A shopkeeper's monthly ledger is exactly such a table — items in rows, months in columns. Adding a row tells him a product's yearly sale; adding a column tells him a month's total business.

📝 Exam-Level Example

Q. Using the same table (A = 120, 150, 180 for 2021, 2022, 2023), find the average yearly sales of company A.

1. Total of A = 120 + 150 + 180 = 450
2. Average = 450 ÷ 3

Answer: ₹150 crore

📝 Exam-Level Example

Q. In which year was the combined sales of all four companies the highest? (A = 120,150,180; B = 200,180,220; C = 90,140,160; D = 160,200,240)

1. 2021 total = 120 + 200 + 90 + 160 = 570
2. 2022 total = 150 + 180 + 140 + 200 = 670
3. 2023 total = 180 + 220 + 160 + 240 = 800
4. Highest is 800 → year 2023

Answer: 2023

📝 Exam-Level Example

Q. What is the ratio of company B's sales to company A's sales in 2021? (B = 200, A = 120 in 2021)

1. Ratio = 200 : 120
2. Divide both by 40 → 5 : 3

Answer: 5 : 3

🪄 Memory Trick

Underline exactly which cells the question needs BEFORE calculating — most table mistakes are 'picked the wrong row/column', not wrong arithmetic.

⚠️ Common Mistakes

• ❌ Mixing up rows and columns (company vs year)
• ❌ Reading the wrong year's value
• ❌ Forgetting the unit given in the heading (crore, thousand, %)

🏆 Exam Tips

• ✅ Always note the unit written above the table
• ✅ For 'highest/lowest' questions, jot down each total instead of guessing

📌 Summary

• Read row/column headings before touching numbers
• Row/column total → then average = total ÷ count
• Ratio = simplify the two required cells
• Highest/lowest → compute all needed totals, then compare