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How do you find the geometric mean of a proportion?

Published in Mathematics 2 mins read

To find the geometric mean of two numbers, which are often related in a proportion, you take the square root of their product.

Here's a breakdown:

Understanding Geometric Mean in the Context of a Proportion

A proportion is an equation stating that two ratios are equal, such as a/b = c/d. While the term "geometric mean of a proportion" isn't directly standard, it often refers to finding a value x that creates a continued proportion like a/x = x/b. In this case, x is the geometric mean between a and b.

Calculating the Geometric Mean

  1. Identify the numbers: Determine the two numbers (let's call them p and q) for which you want to find the geometric mean.
  2. Multiply the numbers: Calculate the product of p and q (i.e., p q).
  3. Take the square root: Find the square root of the product calculated in step 2 (i.e., √(p q)). This result is the geometric mean.

Formula

The geometric mean (x) of two numbers p and q is given by:

x = √(p * q)

Example

Let's say you want to find the geometric mean between 4 and 9.

  1. Numbers: p = 4, q = 9
  2. Product: 4 * 9 = 36
  3. Square Root: √36 = 6

Therefore, the geometric mean of 4 and 9 is 6.

Practical Application in Proportions

If you have a proportion a/x = x/b, you're essentially saying that x is the geometric mean between a and b. Solving for x gives you x2 = ab, and therefore x = √(ab).

In conclusion, finding the geometric mean in the context of a proportion typically involves finding the square root of the product of the two relevant numbers that define the proportion, especially when aiming to create a continued proportion.

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