EXAMPLE 3.1.4

The graph below shows information about US households over the period of time beginning in 1910 and ending in 1990. Suppose that the US population in 1990 was roughly 270 million. How many people were classified as "rural."

EXAMPLE 3.1.4 SOLUTION

In order to answer this question, we need to make an assumption: we will assume that the percentage of people who were "rural" is about the same as the percentage of households that were rural (this may or may not be a reasonable assumption, but unless we make this assumption the graph will not provide enough information for us to be able to answer the question).

The graphs shows that approximately 21% of US households were "rural" in 1990. Assuming that 21% of the population were also "rural," we have:

21% of 270 million

= .21(270,000,000)

= 56,700,000

or 56.7 million people