Dot Plots

Show your work for each problem.

1.
In a dot plot, what does each dot represent?
1. a)One data point
2. b)The total count
3. c)The average
4. d)Ten data points
Answer: One data point
In a dot plot, each dot represents exactly one piece of data. If 5 people chose blue, there would be 5 dots above blue.
2.
A dot plot shows: 3 dots above 5, 2 dots above 6, 4 dots above 7. What is the mode?
1. a)5
2. b)6
3. c)7
4. d)4
Answer: 7
The mode is the value that appears most often. Since 7 has 4 dots (more than 5's 3 dots or 6's 2 dots), the mode is 7.
3.
A dot plot shows test scores: 5 dots above 80, 3 dots above 90, 2 dots above 100. How many students took the test?
Answer: 10
Each dot represents one student. Total students = students.
4.
A dot plot shows hours of sleep: 2 dots above 7, 6 dots above 8, 4 dots above 9. What is the range?
Answer: 2
Range = highest - lowest = hours.
5.
What is another name for a dot plot?
1. a)Pie chart
2. b)Scatter plot
3. c)Line plot
4. d)Histogram
Answer: Line plot
A dot plot is also called a line plot because the dots are placed above a number line.
6.
Data: 4, 5, 5, 6, 5, 4, 7, 5, 6, 4. Find the mode and range.
Answer: Mode: 5, Range: 3
1. How many times does 4 appear? 3
2. How many times does 5 appear? 4
3. Which value appears most often (mode)? 5
4. What is the range (highest - lowest)? 3
7.
A dot plot shows ages: 1 dot above 10, 3 dots above 11, 5 dots above 12, 2 dots above 13, 1 dot above 14. What is the mode?
Answer: 12
The value 12 has 5 dots, which is more than any other value. Therefore, the mode is 12.
8.
A dot plot shows shoe sizes. There are 0 dots above size 5. What does this mean?
1. a)There is an error in the graph
2. b)Size 5 is the mode
3. c)No one has shoe size 5
4. d)Size 5 is the most common
Answer: No one has shoe size 5
Zero dots above a value means that value does not appear in the data. No one in the survey has shoe size 5. This is called a gap in the data.
9.
Create a frequency table for this data: 2, 3, 3, 4, 3, 2, 4, 4, 3, 5. Then find the total count.
Answer: 10
1. How many 2s are in the data? 2
2. How many 3s are in the data? 4
3. How many 4s are in the data? 3
4. How many 5s are in the data? 1
5. What is the total count? (Add all frequencies) 10
10.
A dot plot shows goals scored: 4 dots above 0, 6 dots above 1, 3 dots above 2, 2 dots above 3. How many games were played?
Answer: 15
Total games = total dots = games.
11.
Class A: 70(2), 80(4), 90(3), 100(1). Class B: 70(1), 80(3), 90(4), 100(2). Which class has a higher mode?
Answer: Class B
1. What is the mode for Class A? (value with most dots) 80
2. What is the mode for Class B? (value with most dots) 90
3. Which class has the higher mode? B
12.
A dot plot shows quiz scores: 6(2), 7(3), 8(5), 9(4), 10(1). If one more student scores 7, does the mode change?
Answer: No
1. What is the current mode? 8
2. If one student scores 7, how many dots will be above 7? 4
3. Is 4 more than 5? no
4. Does the mode change? no
13.
A dot plot shows pet counts: 0(3), 1(7), 2(4), 3(2), 4(1). How many more people have 1 pet than have 3 pets?
Answer: 5
People with 1 pet: 7. People with 3 pets: 2. Difference = more people.
14.
Data: 1, 2, 2, 3, 3, 3, 4, 4, 5. A cluster is a group of values close together with many dots. Where is the cluster in this data?
Answer: 2 to 4
1. How many dots are above 1? 1
2. How many dots are above 2? 2
3. How many dots are above 3? 3
4. How many dots are above 4? 2
5. Which values (2, 3, 4) have the most dots close together? 2 to 4
15.
A dot plot shows book lengths: 100(2), 150(0), 200(5), 250(0), 300(3). What does the pattern of gaps tell us?
1. a)150 is the mode
2. b)The data has errors
3. c)All books are the same length
4. d)No books have 150 or 250 pages
Answer: No books have 150 or 250 pages
Gaps at 150 and 250 (0 dots) show that no books in the data set have those page counts. This is valuable information - it shows what values are NOT present.