Regression lines and residuals

Answer Key - Grade 9 Math Worksheet - Building Confidence

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

1. 1.

   Milo plotted a puppy's weight. The line predicts 18.4 at x = 10, and the dot there is at y = 19.4. What is the residual at x = 10?

   1
2. 2.

   Noah plotted a tomato plant's height. The line predicts 42 at x = 5, and the dot there is at y = 40.4. What is the residual at x = 5?

   -1.6
3. 3.

   Pia plotted a candle's height as it burns. The line predicts 19.5 at x = 3, and the dot there is at y = 17.4. What is the residual at x = 3?

   -2.1
4. 4.

   Ren plotted reading time against chapter length. The line predicts 44.1 at x = 18, and the dot there is at y = 45.1. What is the residual at x = 18?

   1
5. 5.

   Zee plotted the height of a stack of paper cups. The calculator's line is y = 1.8x + 6.4. What does the line predict for x = 7?

   19
6. 6.

   Ari plotted kite height against string let out. The calculator's line is y = 0.6x - 3. What does the line predict for x = 35?

   18
7. 7.

   Bo plotted an ice block melting in the sun. The calculator's line is y = -11.5x + 420. What does the line predict for x = 12?

   282
8. 8.

   Esme plotted snow depth as the sun comes out. The residual for the dot at x = 4 is -0.8. What does that mean?

   • The dot is 0.8 centimeters below the line; the line predicted too much.
   • The dot is 0.8 hours to the left of the line.
   • The line is off by 0.8 centimeters at every x.
   • The dot is 0.8 centimeters above the line; the line predicted too little.
9. 9.

   Kira plotted reading time against chapter length. The residual for the dot at x = 12 is -2.2. What does that mean?

   • The line is off by 2.2 minutes at every x.
   • The dot is 2.2 minutes above the line; the line predicted too little.
   • The dot is 2.2 pages to the left of the line.
   • The dot is 2.2 minutes below the line; the line predicted too much.
10. 10.

    Luz plotted a tomato plant's height. The residual for the dot at x = 7 is 1.6. What does that mean?

    • The dot is 1.6 centimeters below the line; the line predicted too much.
    • The dot is 1.6 centimeters above the line; the line predicted too little.
    • The line is off by 1.6 centimeters at every x.
    • The dot is 1.6 weeks to the right of the line.