Math Problem Statement

S^2 (x/2) = 2. Find variance

Solution

To find the variance of S2(x/2)=2S^2(x/2) = 2, let's walk through the interpretation and solution process step by step.

  1. Step 1: Recognizing the notation S2S^2
    Here, S2S^2 is typically used to represent the sample variance of a dataset. Given that it's a function of x2\frac{x}{2}, the equation suggests that the variance of x2\frac{x}{2} is equal to 2.

  2. Step 2: Variance of a scaled random variable
    The variance of a random variable that is scaled by a constant cc follows this rule:
    Var(cX)=c2Var(X)\text{Var}(cX) = c^2 \cdot \text{Var}(X) In this case, X=xX = x and the scaling factor is 12\frac{1}{2}. Therefore,
    Var(x2)=(12)2Var(x)=14Var(x)\text{Var}\left(\frac{x}{2}\right) = \left(\frac{1}{2}\right)^2 \cdot \text{Var}(x) = \frac{1}{4} \cdot \text{Var}(x)

  3. Step 3: Solve for the variance of xx
    From the equation Var(x2)=2\text{Var}\left(\frac{x}{2}\right) = 2, we substitute the variance formula:
    14Var(x)=2\frac{1}{4} \cdot \text{Var}(x) = 2 Now, solve for Var(x)\text{Var}(x): Var(x)=2×4=8\text{Var}(x) = 2 \times 4 = 8

Thus, the variance of xx is 8\boxed{8}.

Would you like more details on this or have any follow-up questions?


Here are 5 related questions that expand on this concept:

  1. How does the variance of a random variable change when multiplied by a constant?
  2. What is the difference between sample variance and population variance?
  3. How do you calculate the variance of a dataset?
  4. Can you explain the properties of variance for independent random variables?
  5. What is the relationship between standard deviation and variance?

Tip: Remember that variance is always non-negative, as it measures the spread of data squared.

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Math Problem Analysis

Mathematical Concepts

Variance
Random Variables
Scaling of Random Variables

Formulas

Var(cX) = c^2 * Var(X)
Var(x/2) = (1/2)^2 * Var(x)

Theorems

Scaling Property of Variance

Suitable Grade Level

College Level or Advanced High School (Grades 11-12)