Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Lesson 7.4 Use Normal Distributions Vocabulary 18.00% 16.00% 14.00% 12.00% • A normal distribution is modeled by a bell-shaped curve called a normal curve that is symmetric about the mean. The total area under the related curve is 1. • The percentage of the area covered by each standard deviation from the mean is shown in the graph 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1 2 3 4 5 6 7 8 9 10 11 12 13 Standard Normal Distribution • The standard normal distribution is the normal distribution with mean 0 and standard deviation 1. • The formula below can be used to transform x-values from a normal distribution with mean x bar and standard deviation sigma into zvalues having a standard normal distribution. z xx z-score z xx • The z-value for a particular x-value is called the z-score for the x-value and is the number of standard deviations the x-value lies above or below the mean . Text p.296 Example 1 Example 2 • Oak Trees The heights (in feet) of fully grown white oak trees are normally distributed with a mean of 90 feet and a standard deviation of 3.5 feet. • About what percent of white oak trees have heights between 86.5 feet and 93.5 feet? Homework • Page 266 1-18