Circle graphs: 100 percent of what?

Example 1

1. A circle graph shows the parts of a whole. Before reading a wedge, ask: 100 percent of what?
2. The label under the circle answers it: all 338.1 million people in the United States. So each wedge is a share of 338.1 million.
3. The small wedge, below the poverty line, is 10.2 percent.
4. To turn a percent back into a count, take that percent of the whole. 10 percent of 338.1 million is 33.8 million; 10.2 percent is a little more, about 34.5 million. So about 34 million people. That is B.
5. A reads the percent as if it were a count of millions. 10.2 is a share, not a number of people.
6. C comes from the other wedge, 89.8 percent, read as millions. D is the whole circle, everyone.
7. Check it with the source: the Census Bureau’s table counts 34,510 thousand people in poverty in 2025, about 34.5 million.

Answer: B

Example 2

1. Ask first: 100 percent of what? The label under the circle says the whole is the 120 tenants who answered.
2. The line under the graph gives another number, 200 tenants in the building. It is a different whole. The circle is not about all 200, only the 120 who answered.
3. The yes wedge is 50 percent: half of the circle. Half of 120 is 60. That is B.
4. C, 100, is 50 percent of 200, the wrong whole. This is the trap Skills Quiz 5 says catches the most people.
5. A reads the percent, 50, as a count. D is the whole building.
6. And one thing the circle cannot tell you: what the 80 tenants who did not answer think. 60 tenants are half of those who answered, but less than a third of the building.

Answer: B