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Grade 9 · Math · Algebra 1

9th grade Regression lines and residuals worksheet

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Regression lines and residuals

Grade 9 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

  1. Noah plotted snow depth as the sun comes out. The dot at x = 7 has a residual of -1, but its label is smudged. What is that dot's y-value?

  2. Pia plotted reading time against chapter length. The dot at x = 14 has a residual of 1.2, but its label is smudged. What is that dot's y-value?

  3. Ren plotted the temperature against cricket chirps. The dot at x = 24 has a residual of -1.8, but its label is smudged. What is that dot's y-value?

  4. Tala plotted a tomato plant's height with its least-squares line. Which dot has the residual farthest from 0? Write it as (x, y).

  5. Zee plotted a candle's height as it burns with its least-squares line. Which dot has the residual farthest from 0? Write it as (x, y).

  6. Ari plotted the height of a stack of paper cups with its least-squares line. Which dot has the residual farthest from 0? Write it as (x, y).

  7. Bo plotted an ice block melting in the sun with its least-squares line. Which dot has the residual farthest from 0? Write it as (x, y).

  8. Esme plotted snow depth as the sun comes out and listed the residuals from the least-squares line. Is a line a good model for these data?

    • No: the line should pass through the first and last dots to be a good model.
    • No: the residuals run in a pattern of signs, so a curve would fit better.
    • Yes: the residuals add up to 0.
    • Yes: some residuals are positive and some are negative.
  9. Jun plotted a tomato plant's height and listed the residuals from the least-squares line. Is a line a good model for these data?

    • No: the line should pass through the first and last dots to be a good model.
    • Yes, because the residuals add up to 0.
    • Yes: the residuals are small and jump above and below 0 with no pattern.
    • No: the residuals are not all 0.
  10. Luz plotted a candle's height as it burns and listed the residuals from the least-squares line. Is a line a good model for these data?

    • No: the line should pass through the first and last dots.
    • Yes: the residuals are small and jump above and below 0 with no pattern.
    • No: the residuals are not all 0.
    • Yes, because the residuals add up to 0.
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9th grade Regression lines and residuals worksheet – printable
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About this worksheet

Regression lines and residuals. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find a residual as observed minus predicted, and say what its sign means.
  • I can say what the slope and the y-intercept of a fitted line mean in the story, or that the intercept means nothing real.
  • I can use the residuals to judge whether a line is a good model.

Standard: S-ID.B.6a–c, S-ID.C.7

Words to know

least-squares (regression) line: The calculator's best line through the dots.

predicted value: The line's y at a given x.

residual: Observed y minus predicted y: the up-or-down gap to the line.

slope (in a story): The typical change in y for one more unit of x.

y-intercept (in a story): The predicted y when x is 0, if that makes sense.

residual pattern: Signs that run in groups, showing the data bend away from the line.

Common mistakes

Your child subtracted in the wrong order, so the residual's sign flipped. A residual is the actual value minus the predicted value; a dot above the line has a positive residual.

Your child multiplied by the slope but left out the y-intercept. Say the line out loud: slope times x, then plus the y-intercept.

Your child multiplied x by the wrong number in the line's equation. The number right next to x is the slope; it is the one that multiplies x.

Questions parents ask

What is the most common mistake with regression lines and residuals?

Your child subtracted in the wrong order, so the residual's sign flipped. A residual is the actual value minus the predicted value; a dot above the line has a positive residual.

Are these 9th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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