Standard Deviation and Variance Exercises

Exercises

Question 1

What is the population standard deviation for the numbers: 75, 83, 96, 100, 121 and 125?

Question 2

A booklet has 12 pages with the following numbers of words:
271, 354, 296, 301, 333, 326, 285, 298, 327, 316, 287 and 314

What is the standard deviation number of words per page?

Question 3

The population standard deviation of the numbers 3, 8, 12, 17, and 25 is 7.563 correct to 3 decimal places.

What happens if each of the five numbers is multiplied by 3?

Standard Deviation and variance

Definitions

Standard Deviation

The Standard Deviation is a measure of how spread out numbers are:

The symbol is σ

Formula: it is the square root of the Variance.  

Variance

The Variance is defined as: 

The average of the squared differences from the Mean.