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Bivariate Data and Scatter Plots Practice Tests

These Grade 8 Math practice tests cover paired numerical data, scatter plots, positive and negative associations, trends, line of best fit, residuals, outliers, and predictions.

Skills covered

  • Reading ordered pairs, tables, domains, and ranges
  • Describing positive, negative, weak, strong, and no association
  • Interpreting clusters, outliers, trend lines, and residuals
  • Distinguishing interpolation, extrapolation, association, and causation
  • Using real-world data to make and evaluate predictions

How to use these practice tests

Read both axes and their units first. Then describe the direction and strength of the association, inspect unusual points, and use a trend line only within a reasonable data range.

For more Grade 8 Math practice, return to the Grade 8 Math category.

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Grade 8 Bivariate Data and Scatter Plots Practice Tests

Practice Grade 8 Math questions about bivariate data, scatter plots, associations, trend lines, residuals, outliers, predictions, and real-world contexts.

Choose the best answer for each question. Identify both variables, read the scale, describe the association, and distinguish association from causation.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

A store records advertising minutes x and sales y. The line of best fit is y=5x+20y=5x+20. What does 20 represent?

Please select an answer first.

Correct answer: A

The correct answer is The predicted sales when advertising time is zero.

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: The y-intercept is the predicted output when x=0.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

The y-intercept is the predicted output when x=0.

2. QuestionMultiple choice

In y=5x+20y=5x+20, what does 5 represent?

Please select an answer first.

Correct answer: B

The correct answer is The predicted increase in sales for each additional minute.

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: The slope is the change in predicted sales for a one-unit increase in advertising time.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

The slope is the change in predicted sales for a one-unit increase in advertising time.

3. QuestionMultiple choice

Using y=5x+20y=5x+20, what is the predicted y-value when x=4x=4?

Please select an answer first.

Correct answer: C

The correct answer is 4040.

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: Substitute 4: y=5(4)+20=40y=5(4)+20=40.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

Substitute 4: y=5(4)+20=40y=5(4)+20=40.

4. QuestionMultiple choice

If the observed value is 44 and the predicted value is 40, what is the residual?

Please select an answer first.

Correct answer: D

The correct answer is 44.

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: Residual = observed - predicted = 44−40=444-40=4.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

Residual = observed - predicted = 44−40=444-40=4.

5. QuestionMultiple choice

A line of best fit has a negative slope. What does that indicate?

Please select an answer first.

Correct answer: A

The correct answer is The predicted response decreases as the explanatory variable increases..

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: A negative slope represents a decreasing predicted trend.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

A negative slope represents a decreasing predicted trend.

6. QuestionMultiple choice

A line of best fit has slope zero. What does that indicate?

Please select an answer first.

Correct answer: B

The correct answer is The predicted response stays constant as x changes..

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: A zero slope produces a horizontal prediction line.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

A zero slope produces a horizontal prediction line.

7. QuestionMultiple choice

Which point is closest to the line y=x+2y=x+2 when x=3x=3?

Please select an answer first.

Correct answer: C

The correct answer is (3,5)(3,5).

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: At x=3, the line predicts y=3+2=5y=3+2=5, so (3,5)(3,5) lies on the line.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

At x=3, the line predicts y=3+2=5y=3+2=5, so (3,5)(3,5) lies on the line.

8. QuestionMultiple choice

A scatter plot has a cluster of points near (10,20)(10,20). What is a cluster?

Please select an answer first.

Correct answer: D

The correct answer is A group of points close together..

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: A cluster is a group of observations concentrated in one region.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

A cluster is a group of observations concentrated in one region.

9. QuestionMultiple choice

A model predicts a value inside the observed x-range. This prediction is:

Please select an answer first.

Correct answer: A

The correct answer is Interpolation.

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: A prediction within the observed range is interpolation.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

A prediction within the observed range is interpolation.

10. QuestionMultiple choice

Why should axes and units be labeled on a scatter plot?

Please select an answer first.

Correct answer: B

The correct answer is To identify what each variable and scale represents..

  1. Identify the two variables: Name the input and output variables and read each ordered pair, table, or graph carefully.
  2. Analyze the association: Labels let the reader interpret the variables, values, and units correctly.
  3. Check the prediction: Decide whether the conclusion is interpolation, extrapolation, association, causation, or an observation about an outlier.

Labels let the reader interpret the variables, values, and units correctly.

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