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Question the-st

3.4 Two-Variable Data & Models - Line of best fit
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The sterplot shows the relationship between two variables, x and y . A line of best fit is also shown.

  • The sterplot has 10 data points.
  • The data points are in a linear pattern trending down from left to right.
  • A line of best fit is shown:
    • The line of best slants down from left to right.
    • 1 point is touching the line of best fit.
    • 4 points are above the line of best fit.
    • 5 points are below the line of best fit.
    • The line of best fit passes through the following approximate coordinates:
      • (2 comma 12)
      • (8 comma 7)
      • (13 comma 3)

Which of the following equations best represents the line of best fit shown?

A.

y=13.5+0.8x

B.

y=13.5-0.8x

C.

y=-13.5+0.8x

D.

y=-13.5-0.8x

The sterplot shows the relationship between two variables, x and y . A line of best

Medium-difficulty · SAT Math · Two-Variable Data & Models — Line of best fit. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice B is correct. The line of best fit shown intersects the y-axis at a positive y-value and has a negative slope. The graph of an equation of the form y=a+bx, where a and b are constants, intersects the y-axis at a y-value of a and has a slope of b . Of the given choices, only choice B represents a line that intersects the y-axis at a positive y-value, 13.5 , and has a negative slope, -0.8 .

Choice A is incorrect. This equation represents a line that has a positive slope, not a negative slope.

Choice C is incorrect. This equation represents a line that intersects the y-axis at a negative y-value, not a positive y-value, and has a positive slope, not a negative slope.

Choice D is incorrect. This equation represents a line that intersects the y-axis at a negative y-value, not a positive y-value.

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