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Arithmetic Mean (AM) for Grouped Data

print("hello world")
for i in range(100):
   print(i)
  • hello
  • hi

This document explains how to calculate the Arithmetic Mean (AM) for grouped frequency data.


✅ Formula:

$$ \text{Arithmetic Mean (AM)} = \frac{1}{N} \sum_{i=1}^{n} f_i x_i $$

Where:

  • AM = Arithmetic Mean
  • fᵢ = Frequency of the i-th class
  • xᵢ = Mid-point (class mark) of the i-th class
  • N = Total frequency (i.e., Σfᵢ)

🧮 Example

Class Interval Frequency (fᵢ) Mid-point (xᵢ) fᵢ × xᵢ
10 – 20 3 15 45
20 – 30 5 25 125
30 – 40 2 35 70
Total 10 240

Calculation:

AM = 240 / 10 = 24



📘 How to Identify Geometric Mean (GM)

The Geometric Mean (GM) is a measure of central tendency used when the data involves products or ratios, such as rates, percentages, growth factors, or logarithmic data.


🔹 Definition

The Geometric Mean of a set of n positive numbers is the nth root of their product:

GM = (x₁ × x₂ × x₃ × ... × xₙ)^(1/n)

Or more compactly:

GM = (∏ xᵢ)^(1/n)


✅ Steps to Identify / Calculate GM (Ungrouped Data)

Given values: x₁, x₂, ..., xₙ

  1. Multiply all the values together:
    P = x₁ × x₂ × ... × xₙ

  2. Take the nth root of the product:
    GM = P^(1/n)


🔹 Logarithmic Method (Preferred for large numbers)

  1. Take the logarithm of each value:
    log(GM) = (1/n) × [log(x₁) + log(x₂) + ... + log(xₙ)]

  2. Take the antilog to get GM:
    GM = antilog { (1/n) × Σ log(xᵢ) }


🧮 Example

Given data: 4, 16, 64

Step 1: Multiply all the values:
4 × 16 × 64 = 4096

Step 2: Take the cube root (since n = 3):
GM = ³√4096 = 16


🧠 When to Use Geometric Mean

  • Rates of change (e.g., growth rates, returns on investment)
  • Percentages or indices
  • Skewed distributions
  • To avoid the influence of extreme values

Feel free to contribute examples or improvements via pull request.

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