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Data Comparison Across Years / Categories

Introduction

பல Data Interpretation (DI) problems-ல், ஆண்டுகள் அல்லது categories-கள் முழுவதும் values-ஐ ஒப்பிட்டு growth, decline, அல்லது relative performance-ஐ கண்டறிய கேட்கப்படும். இந்த pattern முக்கியமானது, ஏனெனில் exams-ல் ranking, fastest growth-ஐ அடையாளம் காணுதல், அல்லது year-on-year changes-ஐ கணக்கிடுதல் போன்றவை அடிக்கடி கேட்கப்படும்.

Pattern: Data Comparison Across Years / Categories

Pattern

ஒரே base period-ஐ பயன்படுத்தி absolute changes மற்றும் percentage changes-ஐ ஒப்பிட்டு fastest/slowest growth அல்லது relative performance-ஐ அடையாளம் காணுங்கள்.

Key formulas:
Absolute change = New value - Old value
Percentage change = (New - Old) ÷ Old × 100

Step-by-Step Example

Question

கீழே உள்ள table-ல் 2019 மற்றும் 2021 ஆண்டுகளில் நான்கு cities-களின் population (’000-ல்) கொடுக்கப்பட்டுள்ளது. 2019 முதல் 2021 வரை எந்த city-க்கு அதிக percentage growth உள்ளது?

City2019 (’000)2021 (’000)
Alpha120132
Beta90108
Gamma150165
Delta8096

Solution

  1. Step 1: ஒவ்வொரு city-க்கும் absolute change-ஐ கணக்கிடுங்கள்:

    Alpha: 132 - 120 = 12 (’000)
    Beta: 108 - 90 = 18 (’000)
    Gamma: 165 - 150 = 15 (’000)
    Delta: 96 - 80 = 16 (’000)

  2. Step 2: 2019-ஐ base-ஆக கொண்டு percentage growth-ஐ கணக்கிடுங்கள்:

    Formula: (New - Old) ÷ Old × 100

    Alpha: (12 ÷ 120) × 100 = 10.00%
    Beta: (18 ÷ 90) × 100 = 20.00%
    Gamma: (15 ÷ 150) × 100 = 10.00%
    Delta: (16 ÷ 80) × 100 = 20.00%

  3. Step 3: Percentage growth values-ஐ ஒப்பிடுங்கள்:

    Beta மற்றும் Delta - இரண்டுக்கும் 20.00% என்ற உயர்ந்த percentage growth உள்ளது.

  4. Final Answer:

    Beta மற்றும் Delta (tie)

  5. Quick Check:

    Beta-க்கு verify செய்யுங்கள்: (108 - 90) ÷ 90 = 18 ÷ 90 = 0.2 = 20% ✅

Quick Variations

1. இரண்டு ஆண்டுகளுக்கு மேல் data-ஐ ஒப்பிடுங்கள் (CAGR அல்லது year-on-year % பயன்படுத்தவும்).

2. Categories-ஐ (எ.கா., product lines) அதே formulas-ஐ பயன்படுத்தி ஒப்பிடுங்கள் - base year அல்லது average என்பதை question wording-க்கு ஏற்ப தேர்வு செய்யுங்கள்.

3. Bases மிகவும் மாறுபட்டால், fair comparison-க்கு percentage change-ஐ பயன்படுத்துங்கள்; unit-based differences-க்கு absolute change-ஐ பயன்படுத்துங்கள்.

Trick to Always Use

  • Step 1: முதலில் absolute change-ஐ கணக்கிட்டு major movers-ஐ கவனிக்கவும்.
  • Step 2: சரியான base year-ஐ பயன்படுத்தி percentage-ஆக மாற்றுங்கள்: (New - Old) ÷ Old × 100.
  • Step 3: Percentage-ல் tie இருந்தால், question “largest increase” என்று குறிப்பிட்டால் absolute changes-ஐ ஒப்பிடுங்கள்.

Summary

Summary

Data Comparison Across Years / Categories pattern-இல்:

  • Raw difference-ஐ காண absolute change = New - Old கணக்கிடுங்கள்.
  • Proportional growth-க்கு percentage change = (New - Old) ÷ Old × 100 கணக்கிடுங்கள்.
  • Fair comparison-க்கு எப்போதும் ஒரே base year-ஐ பயன்படுத்துங்கள்.
  • Values-ஐ ஒப்பிடுவதற்கு முன் units (₹, %, ’000) consistent-ஆக உள்ளதா எனச் சரிபார்க்கவும்.
  • Accuracy-க்காக குறைந்தது ஒரு entry-யை quick verification செய்யுங்கள்.

Practice

(1/5)
1.

School Enrollment - Compare 2018 vs 2020

The table shows student counts in three streams for 2018 and 2020. Which stream had the highest percentage growth from 2018 to 2020?

Stream2018 (students)2020 (students)
Arts1,2001,440
Science1,5001,650
Commerce800880
easy
A. Arts
B. Science
C. Commerce
D. All equal

Solution

  1. Step 1: Compute absolute increases (2020 - 2018):

    Arts: 1,440 - 1,200 = 240 students.
    Science: 1,650 - 1,500 = 150 students.
    Commerce: 880 - 800 = 80 students.

  2. Step 2: Compute percentage growth using 2018 as base:

    Arts: (240 ÷ 1,200) × 100 = 20.00%.
    Science: (150 ÷ 1,500) × 100 = 10.00%.
    Commerce: (80 ÷ 800) × 100 = 10.00%.

  3. Step 3: Compare percentages:

    Highest percentage growth = Arts (20.00%).

  4. Final Answer:

    Arts → Option A.

  5. Quick Check:

    240 ÷ 1,200 = 0.20 → 20% ✅

Hint: Compute absolute change first, then convert to % by dividing by the older year's value.
Common Mistakes: Comparing absolute increases directly instead of percentage when bases differ.
2.

Company Revenues - 2019 vs 2021 (₹ lakh)

The table shows revenues of three companies in 2019 and 2021. Which company had the largest absolute increase in revenue from 2019 to 2021?

Company2019 (₹ lakh)2021 (₹ lakh)
X400500
Y350420
Z300360
easy
A. X
B. Y
C. Z
D. Tie between X & Y

Solution

  1. Step 1: Compute absolute increases (2021 - 2019):

    X: 500 - 400 = 100 (₹ lakh).
    Y: 420 - 350 = 70 (₹ lakh).
    Z: 360 - 300 = 60 (₹ lakh).

  2. Step 2: Identify largest absolute increase:

    Largest increase = 100 (₹ lakh) for Company X.

  3. Final Answer:

    X → Option A.

  4. Quick Check:

    100 > 70 > 60 ✅

Hint: When asked 'largest absolute increase' use raw differences (new - old) rather than %.
Common Mistakes: Mixing up absolute increase with percentage increase.
3.

Product Sales - Yearly Totals (₹ lakh)

The table shows sales of four products across three years. Which year had the highest total sales?

Product2019 (₹ lakh)2020 (₹ lakh)2021 (₹ lakh)
A120140160
B150160170
C8090100
D90100120
easy
A. 2019
B. 2020
C. Cannot determine
D. 2021

Solution

  1. Step 1: Sum totals for each year:

    2019 total = 120 + 150 + 80 + 90 = 440 (₹ lakh).
    2020 total = 140 + 160 + 90 + 100 = 490 (₹ lakh).
    2021 total = 160 + 170 + 100 + 120 = 550 (₹ lakh).

  2. Step 2: Compare yearly totals:

    2019 = 440; 2020 = 490; 2021 = 550 → highest = 2021.

  3. Final Answer:

    2021 → Option D.

  4. Quick Check:

    550 > 490 > 440 ✅

Hint: When asked about 'which year had highest total', sum columns year-wise and compare.
Common Mistakes: Comparing product-wise instead of year-wise totals.
4.

Vehicle Sales by Region - 2017 vs 2019

The table shows vehicle sales (units) in four regions for 2017 and 2019. Which region had the highest percentage growth from 2017 to 2019?

Region2017 (units)2019 (units)
North1,5001,650
South1,2001,560
East900990
West800880
medium
A. North
B. South
C. East
D. West

Solution

  1. Step 1: Compute absolute increases (2019 - 2017):

    North: 1,650 - 1,500 = 150.
    South: 1,560 - 1,200 = 360.
    East: 990 - 900 = 90.
    West: 880 - 800 = 80.

  2. Step 2: Compute percentage growth using 2017 as base:

    North: (150 ÷ 1,500) × 100 = 10.00%.
    South: (360 ÷ 1,200) × 100 = 30.00%.
    East: (90 ÷ 900) × 100 = 10.00%.
    West: (80 ÷ 800) × 100 = 10.00%.

  3. Step 3: Compare percentages:

    Highest percentage growth = South (30.00%).

  4. Final Answer:

    South → Option B.

  5. Quick Check:

    360 ÷ 1,200 = 0.30 → 30% ✅

Hint: When region sizes differ, percentage compares fairly - compute (new - old) ÷ old × 100.
Common Mistakes: Picking the region with largest absolute increase ignoring base sizes.
5.

Company Expenses by Category - 2018 vs 2020 (₹ lakh)

The table shows expenses under categories for 2018 and 2020. Which category recorded the highest percentage increase from 2018 to 2020?

Category2018 (₹ lakh)2020 (₹ lakh)
Sales100130
Admin6066
R&D4064
Marketing5070
medium
A. Sales
B. Admin
C. R&D
D. Marketing

Solution

  1. Step 1: Compute absolute increases (2020 - 2018):

    Sales: 130 - 100 = 30.
    Admin: 66 - 60 = 6.
    R&D: 64 - 40 = 24.
    Marketing: 70 - 50 = 20 (all in ₹ lakh).

  2. Step 2: Compute percentage growth using 2018 as base:

    Sales: (30 ÷ 100) × 100 = 30.00%.
    Admin: (6 ÷ 60) × 100 = 10.00%.
    R&D: (24 ÷ 40) × 100 = 60.00%.
    Marketing: (20 ÷ 50) × 100 = 40.00%.

  3. Step 3: Compare percentages:

    Highest percentage increase = R&D (60.00%).

  4. Final Answer:

    R&D → Option C.

  5. Quick Check:

    24 ÷ 40 = 0.6 → 60% ✅

Hint: Smaller bases can produce larger % growth - always compute percent after finding absolute change.
Common Mistakes: Choosing the largest absolute increase without considering base size.

Mock Test

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