AP Statistics · Topic 2.6

Linear Regression Models Practice

Part of Exploring Two-Variable Data.(DAT-1.C)

Practice questions

17

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Sample questions

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  1. Sample 1difficulty 2/5

    The regression predicts MPG from weight (in 1000 lb units).

    Predicting MPG from weight y-hat = 45 - 6.0 x x = weight (1000 lb) y = MPG

    Interpret the slope -6.0.

    • A

      For each additional MPG, weight decreases by 6

    • B

      For each additional 1000 lb, predicted MPG decreases by 6

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    • C

      MPG decreases by 6% per pound

    • D

      Heavier cars get 6 MPG

    Why

    Slope is the predicted change in MPG (y) per one-unit (1000 lb) increase in x.

  2. Sample 2difficulty 2/5

    A regression predicts highway MPG from car weight in thousands of pounds.

    Predicting MPG from weight (1000 lb) y-hat = 45 - 6.0 x x range: 2.0 to 4.5

    Predict MPG for a car weighing 3,000 lb.

    • A

      39

    • B

      27

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    • C

      21

    • D

      33

    Why

    y-hat = 45 - 6.0(3.0) = 45 - 18 = 27 MPG.

  3. Sample 3difficulty 2/5

    A regression predicts weight from height.

    Predicting weight (lb) from height (in) y-hat = -120 + 4.5 x x range: 60 to 76 inches R-Sq = 64%

    The intercept -120 lb is best described as:

    • A

      The predicted weight when x = 60 inches

    • B

      The slope of the line

    • C

      Not meaningful in context because height = 0 is far outside the data range

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    • D

      The mean weight in the sample

    Why

    Extrapolating to x = 0 (zero inches tall) lies outside the observed range, so the intercept has no real-world meaning here.

  4. Sample 4difficulty 2/5

    For a least-squares regression, x-bar = 10 and y-bar = 25.

    Sample means x-bar = 10 (units) y-bar = 25 (units) Predict y at x = 10 = ?

    What does the line predict at x = 10?

    • A

      0

    • B

      10

    • C

      Cannot be determined

    • D

      25

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    Why

    The least-squares line passes through (x-bar, y-bar), so it predicts y-bar at x-bar.

  5. Sample 5difficulty 2/5

    The y-intercept a in ŷ = a + bx is

    • A

      Always 0

    • B

      Slope of line

    • C

      Mean of x

    • D

      Predicted y when x = 0

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    Why

    Intercept = predicted y at x = 0 (interpret cautiously if x = 0 is far from data).

AP Statistics · 2.6 Linear Regression Models — Practice Questions | Acemy