EXAMPLE 19Obtaining information from graphs and tables
Using the relative frequency distribution in Table 21, what proportion of states in the sample has carbon emissions of 100 million or more metric tons?
Using the histogram in Figure 19a, how many states have carbon emissions between 70 (inclusive) and 90 (not inclusive) million metric tons?
Using the stem-and-leaf display in Figure 25 on page 69, how many precincts had between 22 and 24 (inclusive) dangerous weapons cases?
Now, using the histogram in Figure 19a, can you determine how many states had between 94 and 104 million metric tons of carbon emissions?
Solution
From Table 21, 100 (million) or more metric tons is represented by two classes: 100–109 and 110–119. Adding their relative frequencies gives us the proportion of states with 100 million or more metric tons of carbon emissions: .
From Figure 19a, there are two classes whose values together contain the values 70 to < 90, each of which has a frequency of two. Therefore, there are states with carbon emissions between 70 (inclusive) and 90 (not inclusive) million metric tons.
The stem-and-leaf display shows us that there are precincts with 22, 23, 24, and 24 dangerous weapons cases. This makes four precincts.
It is not possible to answer this question using the histogram because the histogram does not tell us how many states are above or below 94—just how many are in the 90s.