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Statistics

Tamil Nadu Board · Class 9 · Mathematics

Flashcards for Statistics — Tamil Nadu Board Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

45 questions25 flashcards5 concepts

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An illustration comparing raw (ungrouped) data, arrayed data (sorted), and tabulated data (organized in a basic table with categories and totals).
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25 Flashcards
Card 1Arithmetic Mean - Raw Data

Given raw data of marks obtained by 8 students: 45, 52, 38, 52, 60, 52, 48, 55. Calculate the arithmetic mean.

Answer

Step 1: Add all the marks 45 + 52 + 38 + 52 + 60 + 52 + 48 + 55 = 402 Step 2: Count the number of students n = 8 Step 3: Apply the formula: Mean = Σx / n Mean = 402 / 8 = 50.25 Answer: The arithmet…

Card 2Arithmetic Mean - Assumed Mean Method

A cricketer scored 25, 32, 36, 38, 45, 41, 35, 36 in eight T20 matches. Use the Assumed Mean Method with assumed mean = 36 to find the average score.

Answer

Step 1: Choose assumed mean A = 36 Step 2: Calculate deviation (d) for each score: 25-36 = -11, 32-36 = -4, 36-36 = 0, 38-36 = 2 45-36 = 9, 41-36 = 5, 35-36 = -1, 36-36 = 0 Step 3: Find the average …

Card 3Arithmetic Mean - Method Selection

When do you use the Assumed Mean Method instead of the direct method for calculating arithmetic mean?

Answer

Use the Assumed Mean Method when: 1. The numbers are large and numerous (makes calculation easier and reduces errors) 2. You want to save time in computation 3. Direct multiplication of large numbers …

Card 4Arithmetic Mean - Ungrouped Frequency Distribution

Find the arithmetic mean of the following frequency distribution: Height (cm): 140, 142, 150, 148, 145, 147 Frequency: 4, 1, 2, 1, 2, 2

Answer

Step 1: Create a table with fx values Height(x) | Frequency(f) | fx 140 | 4 | 560 142 | 1 | 142 150 | 2 | 300 148 | 1 | 148 145 …

Card 5Arithmetic Mean - Direct Method (Grouped Data)

Calculate the mean age of residents using the Direct Method: Age: 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 No. of Residents: 2, 6, 9, 7, 4, 2

Answer

Step 1: Find the midpoint (x) of each class interval Midpoint = (Lower limit + Upper limit) / 2 Age | No. of Residents(f) | Midvalue(x) | fx 0-10 | 2 | 5 | 10 10-20 | 6 …

Card 6Arithmetic Mean - Assumed Mean Method (Grouped Data)

Calculate the mean using the Assumed Mean Method for this grouped data: Class Interval: 100-120, 120-140, 140-160, 160-180, 180-200, 200-220, 220-240 Frequency: 10, 8, 4, 4, 3, 1, 2

Answer

Step 1: Choose assumed mean A = 170 (middle value) Step 2: Calculate deviation d = x - A and fd Class | f | x | d=x-170 | fd 100-120 | 10 | 110 | -60 | -600 120-140 | 8 | 130 | -40 | -…

Card 7Arithmetic Mean - Step Deviation Method

Find the mean using Step Deviation Method: Class: 0-8, 8-16, 16-24, 24-32, 32-40, 40-48 Frequency: 10, 20, 14, 16, 18, 22

Answer

Step 1: Identify A = 28 (assumed mean) and c = 8 (class width) Step 2: Calculate d = (x-A)/c and fd Class | f | x | d=(x-28)/8 | fd 0-8 | 10 | 4 | -3 | -30 8-16 | 20 | 12 | -2 …

Card 8Arithmetic Mean - Properties

What is the special property of arithmetic mean? If the mean of marks is 22 for observations 21, 30, 22, 16, 24, 28, 18, 17, verify this property.

Answer

Special Property: The sum of deviations of all entries from the arithmetic mean is always ZERO. Mathematically: Σ(xᵢ - Mean) = 0 Verification: Mean = (21+30+22+16+24+28+18+17)/8 = 176/8 = 22 Deviati…

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Frequently Asked Questions

What are the important topics in Statistics for Tamil Nadu Board Class 9 Mathematics?
Key topics in Statistics include Statistics Chapter Overview Mind Map, Statistics Chapter - Complete Concept Map, Mind map showing the types of data collection methods and their categories. These are the concepts Tamil Nadu Board Class 9 examiners draw on most — study them first, then practise related questions.
How to score full marks in Statistics — Tamil Nadu Board Class 9 Mathematics?
Understand the core concepts first, then work through the 45 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Statistics?
There are 25 flashcards for Statistics covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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