Use Linear Models to Make Predictions Practice — Grade 8 math

Lesson 3: Use Linear Models to Make Predictions — Practice Questions

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. 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. 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. 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. Calculate the slope of the line passing through the points $(1, -4)$ and $(5, 8)$. The slope is ___.
6. A scatter plot shows plant height in cm versus weeks of growth. The line of best fit passes through the points $(3, 10)$ and $(7, 18)$. What is the slope of the line? ___
7. A line of best fit for reading speed versus age passes through $(8, 110)$ and $(12, 150)$. Which equation correctly models this line?
- A. y - 110 = 10(x - 8)
- B. y - 8 = 10(x - 110)
- C. y - 110 = 4(x - 8)
- D. y - 150 = 40(x - 12)
8. A line of best fit relates daily website visitors to an advertising budget in dollars. It passes through $(200, 5000)$ and $(500, 11000)$. What is the slope, representing visitors per dollar spent? ___
9. A line of best fit for a scatter plot passes through the points $(4, 50)$ and $(10, 80)$. Which calculation correctly finds the slope of this line?
- A. $m = \frac{80 - 50}{10 - 4}$
- B. $m = \frac{10 - 4}{80 - 50}$
- C. $m = \frac{80 + 50}{10 + 4}$
- D. m = (80 - 50)(10 - 4)
10. A line of best fit relates hours trained ($x$) to race time in minutes ($y$). The line passes through $(5, 30)$ and $(10, 25)$. If the equation is $y - 30 = m(x - 5)$, what is the value of $m$? ___