These 23 problems practice standard 8.SP.A.1: reading and constructing scatter plots, describing positive, negative and no association, telling linear from nonlinear patterns, and spotting clusters and outliers.
The problems start with reading points and move to plotting tables and explaining patterns in context. The last six are word problems with several parts.
Problem 1: Read points on a scatter plot
The scatter plot shows hours studied and quiz scores for 10 students. Write the coordinates of point A and point B, and explain what each one means.
Problem 2: Plot a table of data
The table shows how many hours Ethan biked and how many miles he rode on six trips. Plot the six points on the grid, then describe the association.
| Hours | Miles |
|---|---|
| 1 | 6 |
| 2 | 13 |
| 3 | 17 |
| 4 | 25 |
| 5 | 29 |
| 6 | 36 |
Problem 3: Describe a positive association
Describe the association between hours studied and quiz score in the scatter plot. Tell what it means in this situation.
Problem 4: Describe a negative association
The scatter plot compares the outside temperature with the cups of cocoa a coffee shop sold. Describe the association.
Problem 5: Describe no association
The scatter plot compares shoe size with test score for 10 students. Does it show an association? Explain.
Problem 6: Name the association from a description
Name the association (positive, negative, or none) described in each statement.
- As the number of miles driven increases, the amount of gas left in the tank tends to decrease.
- Taller students tend to have longer arm spans.
- Knowing a student’s birth month tells nothing about her height.
Problem 7: Recognize a nonlinear association
Sofia kicked a soccer ball. The scatter plot shows the height of the ball each second. Is the association linear or nonlinear? Why is it not positive or negative?
Problem 8: Describe a curved negative pattern
The scatter plot shows the value of a car as it ages. Describe the association.
Problem 9: Find the outlier
A coach plotted weekly practice hours and free throws made out of 20. Identify the outlier and explain how you know.
Problem 10: Find the clusters
The scatter plot shows the ages and heights of 12 campers. Describe any clusters and the overall association.
Problem 11: Predict the association
For each pair of variables, tell whether a scatter plot would most likely show a positive association, a negative association, or no association.
- The age of a puppy (in weeks) and its weight
- The number of absences and the final grade in a class
- A student’s shoe size and the number of pets she has
Problem 12: Find the outlier in a table
Noah recorded the weeks since planting and the height of a bean plant (in inches). One measurement is probably a mistake. Find it and explain.
| Weeks | Height (in.) |
|---|---|
| 1 | 3 |
| 2 | 5 |
| 3 | 6 |
| 4 | 8 |
| 5 | 19 |
| 6 | 11 |
| 7 | 12 |
| 8 | 14 |
Problem 13: Plot and describe a table
The table shows the number of days absent and the final grade for eight students. Plot the points and describe the association.
| Days absent | Final grade |
|---|---|
| 0 | 96 |
| 1 | 93 |
| 2 | 90 |
| 3 | 85 |
| 4 | 83 |
| 5 | 78 |
| 6 | 74 |
| 7 | 70 |
Problem 14: True or false about a plot
Use the scatter plot of hours studied and quiz scores. Tell whether each statement is true or false.
- Every student who studied more than 4 hours scored above 80.
- Two students studied 3 hours and earned the same score.
- The plot shows a positive association.
- The student who studied 6 hours had the lowest score.
Problem 15: Find the mistake
Jamal looked at the cocoa plot and said, “Temperature goes up and cups sold goes down, so this is a positive association.” Explain his mistake.
Problem 16: Count points that meet a condition
Use the plot of hours studied and quiz scores. (a) How many students scored at least 80 points? (b) How many students studied 2 hours or less?
Problem 17: Plot and describe a curved pattern
An orchard owner recorded the age of an apple tree and the bushels of apples it produced. Plot the points and describe the association.
| Age (years) | Bushels |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 10 |
| 5 | 14 |
| 6 | 17 |
| 7 | 19 |
| 8 | 20 |
Problem 18: Clusters and association together
The scatter plot shows the weight and gas mileage of eight vehicles. Describe the clusters and the overall association, and suggest why the clusters exist.
Problem 19: Association is not causation
A town found a positive association between monthly ice cream sales and monthly sunburn cases. Does buying ice cream cause sunburn? Explain.
Problem 20: Read the plot in context
The cocoa plot shows daily sales at different temperatures. (a) About how many cups were sold on the 50°F day? (b) About how many on the 70°F day? (c) How many more cups were sold on the cooler day?
Problem 21: Write your own scenario
Describe a situation with a negative association between two variables, and list four data pairs that fit your situation.
Problem 22: Effect of an outlier
The coach learns that the player in the plot with 7 hours and 3 made shots was injured that week. (a) Which point is that? (b) Describe the association for the other eight players.
Problem 23: Describe every feature
The plot shows nine vehicles. Describe the clusters, the outlier, and the overall association. Include the coordinates of the outlier.
See every chapter on the Grade 8 math page.