Section 9.2: Lines of Fit — Practice Questions

1. 1. Using the slope formula, calculate the slope of the line that passes through the points $(-2, 8)$ and $(4, -1)$. The slope is ___.

2. 2. A line has a slope of $5$ and a y-intercept at $(0, -8)$. Which of the following is the equation of this line in slope-intercept form?

   • A. y = -8x + 5
   • B. y = 5x - 8
   • C. y = 5x + 8
   • D. x = 5y - 8

3. 3. A linear equation is given by $4x + 2y = 12$. To find the slope, you must first convert it to slope-intercept form. What is the slope of this line? ___

4. 4. In the slope-intercept form $y = mx + b$, the value of $b$ represents the y-coordinate of the y-intercept. What is the y-intercept of the line with the equation $y = -3x + 7$?

   • A. (0, 7)
   • B. (0, -3)
   • C. (7, 0)
   • D. (-3, 0)

5. 5. Calculate the slope of the line passing through the points $(1, -4)$ and $(5, 8)$. The slope is ___.

6. 6. A line of fit passes through the points $(3, 5)$ and $(8, 15)$. What is the slope of this line? ___

7. 7. A trend line modeling test scores based on hours studied passes through $(1.5, 70.5)$ and $(4.5, 91.5)$. What is the slope of this line?

   • A. 3
   • B. 7
   • C. 21
   • D. 0.14

8. 8. The slope of a regression line is calculated to be $\frac{3}{4}$ and its y-intercept is $5$. Write the equation of the line in slope-intercept form. $y = $ ___

9. 9. When finding the equation for a line of fit, what does the slope formula $m = \frac{y_2 - y_1}{x_2 - x_1}$ represent?

   • A. The point where the line crosses the y-axis.
   • B. The rate of vertical change relative to horizontal change.
   • C. The horizontal distance between the two points.
   • D. The average of the y-coordinates.

10. 10. A line of fit modeling plant growth passes through points $(10, 8.5)$ and $(30, 14.5)$, where $x$ is days and $y$ is height in cm. What is the equation of the line?

    • A. $y = 0.3x + 5.5$
    • B. $y = 0.3x + 8.5$
    • C. $y = 3.33x + 5.5$
    • D. $y = 6x + 20$