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

We will calculate the sample variance and the sample standard deviation for the given data set since "sample" is indicated.

The steps to calculate sample variance and standard deviation are as follows:

1. Find the sample mean (xˉ\bar{x}):

xˉ=xin\bar{x} = \frac{\sum x_i}{n}

Where:

  • xi\sum x_i is the sum of the sample values
  • nn is the number of sample points

Given sample: 6, 52, 13, 49, 35, 25, 31, 29, 31, 29 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 n=10n = 10 xˉ=30010=30\bar{x} = \frac{300}{10} = 30

2. Calculate the squared deviations from the mean:

For each data point xix_i, calculate (xixˉ)2(x_i - \bar{x})^2:

(630)2=(24)2=576(6 - 30)^2 = (-24)^2 = 576 (5230)2=(22)2=484(52 - 30)^2 = (22)^2 = 484 (1330)2=(17)2=289(13 - 30)^2 = (-17)^2 = 289 (4930)2=(19)2=361(49 - 30)^2 = (19)^2 = 361 (3530)2=(5)2=25(35 - 30)^2 = (5)^2 = 25 (2530)2=(5)2=25(25 - 30)^2 = (-5)^2 = 25 (3130)2=(1)2=1(31 - 30)^2 = (1)^2 = 1 (2930)2=(1)2=1(29 - 30)^2 = (-1)^2 = 1 (3130)2=(1)2=1(31 - 30)^2 = (1)^2 = 1 (2930)2=(1)2=1(29 - 30)^2 = (-1)^2 = 1

3. Sum of squared deviations:

(xixˉ)2=576+484+289+361+25+25+1+1+1+1=1764\sum (x_i - \bar{x})^2 = 576 + 484 + 289 + 361 + 25 + 25 + 1 + 1 + 1 + 1 = 1764

4. Compute the sample variance (s2s^2):

s2=(xixˉ)2n1s^2 = \frac{\sum (x_i - \bar{x})^2}{n - 1} s2=1764101=17649=196s^2 = \frac{1764}{10 - 1} = \frac{1764}{9} = 196

5. Compute the sample standard deviation (ss):

s=s2=196=14s = \sqrt{s^2} = \sqrt{196} = 14

Summary:

  • Sample variance (s2s^2): 196
  • Sample standard deviation (ss): 14

Would you like more details or have any questions?


Here are 5 related questions to expand on this topic:

  1. How do we calculate population variance and standard deviation?
  2. What is the difference between population and sample variance?
  3. Why do we divide by n1n-1 instead of nn in the sample variance formula?
  4. How does the variance change if an outlier is added to the dataset?
  5. What are the applications of standard deviation in real-world scenarios?

Tip: The standard deviation gives insight into how spread out the values in a dataset are. A smaller standard deviation indicates that data points tend to be closer to the mean.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Statistics
Variance
Standard Deviation
Sample Statistics

Formulas

Sample mean formula: x̄ = (Σx_i) / n
Sample variance formula: s² = Σ(x_i - x̄)² / (n - 1)
Sample standard deviation formula: s = √s²

Theorems

Law of Large Numbers (related to sample statistics)

Suitable Grade Level

Grades 10-12