Math Problem Statement

by hand, find the population variance and standard deviation or the sample variance and standard deviation as indicated. Sample: 6, 52, 13, 49, 35, 25, 31, 29, 31, 29

Solution

Let's go through the process of calculating the sample variance and standard deviation by hand for the given sample:

6,52,13,49,35,25,31,29,31,296, 52, 13, 49, 35, 25, 31, 29, 31, 29

Step 1: Find the Sample Mean

The first step is to calculate the mean of the sample. The formula for the sample mean (xˉ\bar{x}) is:

xˉ=xin\bar{x} = \frac{\sum x_i}{n}

where xix_i are the sample values and nn is the sample size.

Here, n=10n = 10, and the sum of the sample values is:

xi=6+52+13+49+35+25+31+29+31+29=300\sum x_i = 6 + 52 + 13 + 49 + 35 + 25 + 31 + 29 + 31 + 29 = 300

Now, calculate the sample mean:

xˉ=30010=30\bar{x} = \frac{300}{10} = 30

Step 2: Calculate Each Deviation from the Mean

Next, subtract the sample mean from each data point to find the deviations:

x1xˉ=630=24x_1 - \bar{x} = 6 - 30 = -24 x2xˉ=5230=22x_2 - \bar{x} = 52 - 30 = 22 x3xˉ=1330=17x_3 - \bar{x} = 13 - 30 = -17 x4xˉ=4930=19x_4 - \bar{x} = 49 - 30 = 19 x5xˉ=3530=5x_5 - \bar{x} = 35 - 30 = 5 [ x_6 - \bar{x} = 25 -

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Math Problem Analysis

Mathematical Concepts

Statistics
Variance
Standard Deviation

Formulas

Sample Mean: \(\bar{x} = \frac{\sum x_i}{n}\)
Sample Variance: \(s^2 = \frac{\sum (x_i - \bar{x})^2}{n - 1}\)
Sample Standard Deviation: \(s = \sqrt{s^2}\)

Theorems

Properties of Variance and Standard Deviation

Suitable Grade Level

Grades 9-12