Regression lines and residuals
Grade 9 Math Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.
Milo plotted a puppy's weight. The dot at x = 13 has a residual of 1, but its label is smudged. What is that dot's y-value?
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?
Scatter plot on a dot grid. Across (x): hours after the snow stopped, from 0 to 12, a tick every 2. Up (y): snow depth in cm, from 0 to 35, a tick every 5. Each dot is one reading. The dots you can read: (0, 28.4), (2, 28.1), (3, 22.4), (4, 20.2), (6, 17), (8, 7.9), (10, 7.8). One more dot, at x = 7, has a smudged label. The least-squares line for all 8 dots is y = -2.4x + 30. Scatter plot on a dot grid. Across (x): hours after the snow stopped, from 0 to 12, a tick every 2. Up (y): snow depth in cm, from 0 to 35, a tick every 5. Each dot is one reading. The dots you can read: (0, 28.4), (2, 28.1), (3, 22.4), (4, 20.2), (6, 17), (8, 7.9), (10, 7.8). One more dot, at x = 7, has a smudged label. The least-squares line for all 8 dots is y = -2.4x + 30. 0 2 4 6 8 10 12 0 5 10 15 20 25 30 35 hours after the snow stopped snow depth in cm y = -2.4x + 30 Each dot is one reading. One more dot, at x = 7, has a smudged label. 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?
Scatter plot on a dot grid. Across (x): pages in the chapter, from 5 to 25, a tick every 5. Up (y): minutes to read it, from 0 to 60, a tick every 5. Each dot is one chapter. The dots you can read: (8, 22.2), (10, 26.9), (12, 30.9), (16, 38.8), (18, 42.5), (22, 51.7), (24, 59.3). One more dot, at x = 14, has a smudged label. The least-squares line for all 8 dots is y = 2.2x + 4.5. Scatter plot on a dot grid. Across (x): pages in the chapter, from 5 to 25, a tick every 5. Up (y): minutes to read it, from 0 to 60, a tick every 5. Each dot is one chapter. The dots you can read: (8, 22.2), (10, 26.9), (12, 30.9), (16, 38.8), (18, 42.5), (22, 51.7), (24, 59.3). One more dot, at x = 14, has a smudged label. The least-squares line for all 8 dots is y = 2.2x + 4.5. 5 10 15 20 25 0 5 10 15 20 25 30 35 40 45 50 55 60 pages in the chapter minutes to read it y = 2.2x + 4.5 One more dot, at x = 14, has a smudged label. Each dot is one chapter. 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?
Scatter plot on a dot grid. Across (x): cricket chirps in 15 seconds, from 15 to 45, a tick every 5. Up (y): temperature in °F, from 50 to 90, a tick every 5. Each dot is one evening. The dots you can read: (18, 52.8), (20, 54.8), (26, 61.9), (30, 68.5), (32, 71.1), (35, 73.8), (40, 77.1). One more dot, at x = 24, has a smudged label. The least-squares line for all 8 dots is y = 1.2x + 31. Scatter plot on a dot grid. Across (x): cricket chirps in 15 seconds, from 15 to 45, a tick every 5. Up (y): temperature in °F, from 50 to 90, a tick every 5. Each dot is one evening. The dots you can read: (18, 52.8), (20, 54.8), (26, 61.9), (30, 68.5), (32, 71.1), (35, 73.8), (40, 77.1). One more dot, at x = 24, has a smudged label. The least-squares line for all 8 dots is y = 1.2x + 31. Each dot is one evening. 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 cricket chirps in 15 seconds temperature in degF y = 1.2x + 31 One more dot, at x = 24, has a smudged label. The least-squares line is for all 8 dots. 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).
Scatter plot on a dot grid. Across (x): weeks since planting, from 0 to 9, a tick every 1. Up (y): plant height in cm, from 0 to 70, a tick every 10. Each dot is one measurement. The dots, left to right: (1, 16.7), (2, 23.1), (3, 29.3), (4, 32.8), (5, 40.2), (6, 50.5), (7, 57.2), (8, 60.2). The calculator's least-squares line is y = 6.5x + 9.5. Scatter plot on a dot grid. Across (x): weeks since planting, from 0 to 9, a tick every 1. Up (y): plant height in cm, from 0 to 70, a tick every 10. Each dot is one measurement. The dots, left to right: (1, 16.7), (2, 23.1), (3, 29.3), (4, 32.8), (5, 40.2), (6, 50.5), (7, 57.2), (8, 60.2). The calculator's least-squares line is y = 6.5x + 9.5. Scatter plot on a dot grid 0 1 2 3 4 5 6 7 8 9 0 10 20 30 40 50 60 70 weeks since planting plant height in cm y = 6.5x + 9.5 Each dot is one measurement. The calculator's least-squares line is shown. 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).
Scatter plot on a dot grid. Across (x): hours burned, from 0 to 8, a tick every 1. Up (y): candle height in cm, from 0 to 30, a tick every 5. Each dot is one check. The dots, left to right: (0, 24.2), (1, 21.2), (2, 21), (3, 19.9), (4, 18.8), (5, 18.4), (6, 13.6), (7, 12.9). The calculator's least-squares line is y = -1.5x + 24. Scatter plot on a dot grid. Across (x): hours burned, from 0 to 8, a tick every 1. Up (y): candle height in cm, from 0 to 30, a tick every 5. Each dot is one check. The dots, left to right: (0, 24.2), (1, 21.2), (2, 21), (3, 19.9), (4, 18.8), (5, 18.4), (6, 13.6), (7, 12.9). The calculator's least-squares line is y = -1.5x + 24. Scatter plot on a dot grid; each dot is one check 0 1 2 3 4 5 6 7 8 0 5 10 15 20 25 30 hours burned candle height in cm y = -1.5x + 24 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).
Scatter plot on a dot grid. Across (x): cups in the stack, from 0 to 14, a tick every 2. Up (y): stack height in cm, from 0 to 30, a tick every 5. Each dot is one stack. The dots, left to right: (2, 10.3), (4, 13.5), (5, 15.8), (6, 16.3), (8, 20.8), (9, 23), (10, 24), (12, 28.3). The calculator's least-squares line is y = 1.8x + 6.4. Scatter plot on a dot grid. Across (x): cups in the stack, from 0 to 14, a tick every 2. Up (y): stack height in cm, from 0 to 30, a tick every 5. Each dot is one stack. The dots, left to right: (2, 10.3), (4, 13.5), (5, 15.8), (6, 16.3), (8, 20.8), (9, 23), (10, 24), (12, 28.3). The calculator's least-squares line is y = 1.8x + 6.4. 0 2 4 6 8 10 12 14 0 5 10 15 20 25 30 cups in the stack stack height in cm y = 1.8x + 6.4 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).
Scatter plot on a dot grid. Across (x): minutes in the sun, from 0 to 40, a tick every 5. Up (y): ice block mass in grams, from 0 to 500, a tick every 50. Each dot is one weighing. The dots, left to right: (0, 427.3), (5, 351.2), (10, 300.7), (15, 249.8), (20, 203.6), (25, 125.5), (30, 77.2), (35, 14.7). The calculator's least-squares line is y = -11.5x + 420. Scatter plot on a dot grid. Across (x): minutes in the sun, from 0 to 40, a tick every 5. Up (y): ice block mass in grams, from 0 to 500, a tick every 50. Each dot is one weighing. The dots, left to right: (0, 427.3), (5, 351.2), (10, 300.7), (15, 249.8), (20, 203.6), (25, 125.5), (30, 77.2), (35, 14.7). The calculator's least-squares line is y = -11.5x + 420. 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 400 450 500 minutes in the sun ice block mass in grams y = -11.5x + 420 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?
Scatter plot on a dot grid. Across (x): hours after the snow stopped, from 0 to 7, a tick every 1. Up (y): snow depth in cm, from 0 to 35, a tick every 5. Each dot is one reading. The dots, left to right: (0, 28), (1, 27.6), (2, 26.4), (3, 24.4), (4, 21.6), (5, 18), (6, 13.6). The calculator's least-squares line is y = -2.4x + 30. Residuals, left to right: -2, 0, 1.2, 1.6, 1.2, 0, -2. Scatter plot on a dot grid. Across (x): hours after the snow stopped, from 0 to 7, a tick every 1. Up (y): snow depth in cm, from 0 to 35, a tick every 5. Each dot is one reading. The dots, left to right: (0, 28), (1, 27.6), (2, 26.4), (3, 24.4), (4, 21.6), (5, 18), (6, 13.6). The calculator's least-squares line is y = -2.4x + 30. Residuals, left to right: -2, 0, 1.2, 1.6, 1.2, 0, -2. 0 1 2 3 4 5 6 7 0 5 10 15 20 25 30 35 hours after the snow stopped snow depth in cm y = -2.4x + 30 Residuals, left to right: -2, 0, 1.2, 1.6, 1.2, 0, -2. - Yes: some residuals are positive and some are negative.
- 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.
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?
Scatter plot on a dot grid. Across (x): weeks since planting, from 0 to 9, a tick every 1. Up (y): plant height in cm, from 0 to 70, a tick every 10. Each dot is one measurement. The dots, left to right: (1, 15.3), (2, 22.3), (3, 29.6), (4, 35.9), (5, 42.6), (6, 48.3), (7, 55.1), (8, 60.9). The calculator's least-squares line is y = 6.5x + 9.5. Residuals, left to right: -0.7, -0.2, 0.6, 0.4, 0.6, -0.2, 0.1, -0.6. Scatter plot on a dot grid. Across (x): weeks since planting, from 0 to 9, a tick every 1. Up (y): plant height in cm, from 0 to 70, a tick every 10. Each dot is one measurement. The dots, left to right: (1, 15.3), (2, 22.3), (3, 29.6), (4, 35.9), (5, 42.6), (6, 48.3), (7, 55.1), (8, 60.9). The calculator's least-squares line is y = 6.5x + 9.5. Residuals, left to right: -0.7, -0.2, 0.6, 0.4, 0.6, -0.2, 0.1, -0.6. 0 1 2 3 4 5 6 7 8 9 0 10 20 30 40 50 60 70 weeks since planting plant height in cm y = 6.5x + 9.5 Each dot is one measurement. Residuals, left to right: -0.7, -0.2, 0.6, 0.4, 0.6, -0.2, 0.1, -0.6. - Yes: the residuals are small and jump above and below 0 with no pattern.
- Yes, because the residuals add up to 0.
- No: the line should pass through the first and last dots to be a good model.
- No: the residuals are not all 0.