3B Circle Graphs
COLORS Use the graph that shows the results of a survey.
a. What color is most favored?
b. If 400 people were surveyed, how many more people favored purple than red?
a. The largest section on the circle graph is the one representing blue. So, blue is the most favored color.
b. Red: 18% of 400 = 0.18 400 or 72
Purple: 28% of 400 = 0.28 400 or 112
There were 112 72, or 40 more people who favored purple than red.
LANDFILLS Use the circle graph that shows what is in U.S. landfills.
a. What takes up the most space in landfills?
b. About how many times more paper is there than food and yard waste?
c. If a landfill contains 200 million tons of trash, how much of it is plastic?
a. The largest section on the graph is the one representing paper. So, paper takes up the most space in landfills.
b. 11% is approximately 10%, and 30% is 3 times 10%. So, there is about 3 times more paper in landfills than food
and yard waste.
c. Find 24% of 200.
24% of 200 = 0.24 200 or 48
So, if a landfill contains 200 million tons of trash, 48 million tons of it is plastic.
MONEY Use the graph that shows the results of a survey.
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3B
b. 11% is approximately 10%, and 30% is 3 times 10%. So, there is about 3 times more paper in landfills than food
and yard waste.
c. Find 24% of 200.
24% of 200
= 0.24 200 or 48
Circle
Graphs
So, if a landfill contains 200 million tons of trash, 48 million tons of it is plastic.
MONEY Use the graph that shows the results of a survey.
a. What percent of Americans favor a common North American currency?
b. About how many of the approximately 298 million Americans would say Don t Know in response to this
survey?
c. About how many more Americans oppose a common currency than favor it?
a. Look at the title of the graph. It asks Do Americans Favor Common North American Currency? The section
that says Yes represents the percent of Americans who do favor a common North American currency. The
number there is 43%. So, 43% of Americans favor a common North American currency.
b. Find 4% of 298 million.
4% of 298 = 0.04 298 or 11.92
So, about 12 million Americans would say Don t Know in response to this survey.
c. Yes: 43% of 298 million = 0.43 298 million or about 130 million
No: 53% of 298 million = 0.53 298 million or about 160 million
There are 160 million 130 million, or about 30 million more Americans who oppose a common currency than favor
it.
DATA SENSE Find the missing value.
The entire circle graph represents 100%. Add the given percentages and find the amount needed to reach 100%.
So, x = 15.
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3B Circle
Graphs
So, x = 15.
The entire circle graph represents 100%. Add the given percentages and find the amount needed to reach 100%.
So, x = 40.
POLITICS A group of students was asked whether people their age could make a difference in the political
decisions of elected officials. The results are shown in the graph.
a. How many students participated in the survey?
b. Write a convincing argument explaining whether or not it is reasonable to say that 50% more students said they
could make a difference than those who said they could not make a difference.
a. Find the total number of students.
366 + 126 + 10 = 502
So, 502 students participated in the survey.
b. Before making an argument, find what a 50% increase would be in 126 students.
Add the percent to 100%
50% + 100% = 150%
Find 150% of 126.
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150% of 126 = 1.5 126 = 189
So, a 50% increase in 126 students is 189 students.
Sample argument: A 50% increase in 126 students is 189 students, and 189 students is not equal to or close to 366
3B Circle Graphs
So, x = 40.
POLITICS A group of students was asked whether people their age could make a difference in the political
decisions of elected officials. The results are shown in the graph.
a. How many students participated in the survey?
b. Write a convincing argument explaining whether or not it is reasonable to say that 50% more students said they
could make a difference than those who said they could not make a difference.
a. Find the total number of students.
366 + 126 + 10 = 502
So, 502 students participated in the survey.
b. Before making an argument, find what a 50% increase would be in 126 students.
Add the percent to 100%
50% + 100% = 150%
Find 150% of 126.
150% of 126 = 1.5 126 = 189
So, a 50% increase in 126 students is 189 students.
Sample argument: A 50% increase in 126 students is 189 students, and 189 students is not equal to or close to 366
students. So, it is not reasonable to say that 50% more students said they could make a difference.
CHALLENGE The graph shows the results of a survey about students favorite school subjects.
About what percent of those surveyed said that math was their favorite subject? Explain your reasoning.
Look at the circle graph.
The part that represents English is half the circle. The part that represents Science is a quarter of the circle. The
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parts that represent Math and Other together are a quarter of the circle. Since the part that represents Math is half
of a quarter, half of 25% or 12.5% of those surveyed said that math was their favorite subject.
Sample explanation. English is half of the circle. Since Science is half of English, Science is half of 50% or 25%.
3B
Find 150% of 126.
150% of 126 = 1.5 126 = 189
So, a 50% increase in 126 students is 189 students.
Sample argument:
Circle
GraphsA 50% increase in 126 students is 189 students, and 189 students is not equal to or close to 366
students. So, it is not reasonable to say that 50% more students said they could make a difference.
CHALLENGE The graph shows the results of a survey about students favorite school subjects.
About what percent of those surveyed said that math was their favorite subject? Explain your reasoning.
Look at the circle graph.
The part that represents English is half the circle. The part that represents Science is a quarter of the circle. The
parts that represent Math and Other together are a quarter of the circle. Since the part that represents Math is half
of a quarter, half of 25% or 12.5% of those surveyed said that math was their favorite subject.
Sample explanation. English is half of the circle. Since Science is half of English, Science is half of 50% or 25%.
Math is half of Science which is half of 25% or 12.5%.
The graph shows the types of vehicles that crossed a bridge during one month.
Which of the following shows the number of trucks if 480,000 vehicles cross the bridge each month?
A. 57,600
B. 72,000
C. 115,200
D. 235,200
Find 24% of 480,000.
24% of 480,000 = 0.24 480,000 or 115,200
So, 115,200 trucks cross the bridge each month. The answer is C.
GRIDDED RESPONSE The circle graph shows the results of a survey in which middle school students were
asked to name one of their favorite pizza toppings. What percent of the people surveyed named mushrooms as their
favorite topping?
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3B
Find 24% of 480,000.
24% of 480,000
= 0.24 480,000 or 115,200
Circle
Graphs
So, 115,200 trucks cross the bridge each month. The answer is C.
GRIDDED RESPONSE The circle graph shows the results of a survey in which middle school students were
asked to name one of their favorite pizza toppings. What percent of the people surveyed named mushrooms as their
favorite topping?
The entire circle graph represents 100%. Add the given percentages and find the amount needed to reach 100%.
So, x = 16.
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