Question

Interpreting Normal Quantile Plots. In Exercises 5–8, examine the normal quantile plot and determine whether the sample data appear to be from a population with a normal distribution.Ages of Presidents The normal quantile plot represents the ages of presidents of the United States at the times of their inaugurations. The data are from Data Set 15 “Presidents” in Appendix B.

Short answer

Since the points on the plot lie lose to the straight line, the sample of the ages of US presidents at the time of their inaugurations appears to be from a normally distributed population.

Step-by-step solution

Given information

A normal quantile plot is given for the sample of the ages of US presidents at the time of their inaugurations.

Interpretation of normal quantile plot

The normal quantile plot is used to assess whether the sample comes from a normally distributed population or not.

• If the data points on the plot lie very close to a straight-line pattern, the sample can be assumed to be from a normally distributed population.
• But if the points follow any other specific pattern, the sample is not from a normally distributed population.

The plot shows that almost all the points lie along a straight line.

Therefore, the sample of the ages ofpresidents of the US at the time of their inaugurations is from a normally distributed population.