Math Problem Statement

For the data below, which represents a sample with n = 8, answer the questions. Round to 4 decimal places where possible.

x 27.7 10.9 18.9 18 11.7 27.2 10.3 4.8 Find the standard deviation

Solution

To find the standard deviation of the given data set, we'll follow these steps:

  1. Calculate the mean (xˉ\bar{x}): xˉ=xn\bar{x} = \frac{\sum x}{n} where x\sum x is the sum of all data points, and nn is the sample size.

  2. Find the squared deviations from the mean: (xixˉ)2(x_i - \bar{x})^2 for each data point xix_i.

  3. Calculate the variance: Variance=(xixˉ)2n1\text{Variance} = \frac{\sum (x_i - \bar{x})^2}{n-1} Since this is a sample, we use n1n-1 in the denominator for the sample variance.

  4. Find the standard deviation: Standard Deviation=Variance\text{Standard Deviation} = \sqrt{\text{Variance}}

Let's perform the calculations.The calculations are as follows:

  1. Mean (xˉ\bar{x}): 16.187516.1875
  2. Variance: 68.127068.1270
  3. Standard deviation: 8.25398.2539

The standard deviation of the sample is approximately 8.2539.

Would you like more details or have any questions? Here are some related questions to deepen your understanding:

  1. How do the mean and standard deviation help in understanding the data set?
  2. What is the difference between population and sample standard deviation?
  3. How does the standard deviation change if we add a new data point?
  4. Why do we divide by n1n-1 instead of nn in the sample variance formula?
  5. What does a higher standard deviation indicate in a data set?

Tip: The standard deviation measures how spread out the numbers are from the mean—larger values indicate more variability in the data.

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Math Problem Analysis

Mathematical Concepts

Statistics
Data Analysis

Formulas

Mean formula: x̄ = Σx / n
Variance formula: σ² = Σ(xi - x̄)² / (n-1)
Standard deviation formula: σ = √(variance)

Theorems

Central Limit Theorem (indirectly related to understanding sample vs. population variance)

Suitable Grade Level

Grades 10-12