Measures of the Spread of the Data · Exercise 18

A selection of countries has poverty rates that range from 11.4% to 74.6%. This data is summarized in Table 2.76.

$$\begin{array}{cc}\text{Percent of Population}& \text{Number of Countries}\\ \text{11.4–20.45}& \text{29}\\ \text{20.45–29.45}& \text{13}\\ \text{29.45–38.45}& \text{4}\\ \text{38.45–47.45}& \text{0}\\ \text{47.45–56.45}& \text{2}\\ \text{56.45–65.45}& \text{1}\\ \text{65.45–74.45}& \text{0}\\ \text{74.45–83.45}& \text{1}\end{array}$$
What is the best estimate of the average poverty percentage for these countries? What is the standard deviation for the listed poverty rates? The United States has an average poverty rate of 33.9%. Is this rate above average or below? How “unusual” is the United States’ rate compared to the average rate? Explain.

OpenStax, Introductory Statistics 2e · §2.7 Measures of the Spread of the Data · Exercise 18