More on Normal Distributions: Answers

Saylor Academy

This is a book resource with multiple pages. Navigate between the pages using the buttons.

The standard normal distribution is defined as a normal distribution with a mean of 0 and a standard deviation of 1.
$Z$ is equal to the number of standard deviations below or above the mean. Numbers below the mean have negative $Z$ scores.
25 is 1.5 SDs above the mean: $Z = (X - M)/SD = (25 - 16)/6 = 1.5$
$Z = (X - M)/SD = (6 - 18)/5 = -2.40$ , Look at the table to see that the area below -2.40 is .0082. (This answer can also be found using the Java applet instead of the table.)