What is the primary characteristic that defines the line of best fit for a scatter plot?

It connects the first and last data points.

It is calculated to be as close as possible to all data points.

It is the easiest line to draw by hand.

How is a line of best fit different from a line of fit that is estimated visually?

The line of best fit is always steeper.

The line of best fit is found using a precise mathematical formula.

The line of best fit must pass through the origin $(0,0)$.

The line of best fit can only be used for positive trends.

Scatter Plots and Lines of Fit Practice — Grade 8 math

Lesson 4: Scatter Plots and Lines of Fit — Practice Questions

1. What is the primary characteristic that defines the line of best fit for a scatter plot?
- A. It connects the first and last data points.
- B. It is calculated to be as close as possible to all data points.
- C. It must have a positive slope.
- D. It is the easiest line to draw by hand.
2. The equation $y = -2000x + 28000$ models a car's value in dollars ($y$) after $x$ years. According to this regression line, the car's value decreases by ___ dollars each year.
3. What is the other common name for the line of best fit?
- A. The scatter line
- B. The regression line
- C. The median line
- D. The correlation line
4. A biologist models plant growth with the equation $y = 0.75x + 3$, where $x$ is hours of sunshine and $y$ is growth in cm. According to this model, a plant with zero sunshine would have a starting height of ___ cm.
5. How is a line of best fit different from a line of fit that is estimated visually?
- A. The line of best fit is always steeper.
- B. The line of best fit is found using a precise mathematical formula.
- C. The line of best fit must pass through the origin $(0,0)$.
- D. The line of best fit can only be used for positive trends.
6. What is the primary purpose of creating a scatter plot?
- A. To calculate the exact value of a variable
- B. To solve a system of linear equations
- C. To show the relationship between two variables
- D. To find the average of a single data set
7. When the data points on a scatter plot can be approximated by a straight line, what does this pattern indicate?
- A. A linear trend
- B. A calculation mistake
- C. A random distribution of data
- D. The data is not related
8. A scatter plot is made showing the number of hours a student spends playing video games and their test scores. If more hours of gaming corresponds to lower scores, what type of trend is this?
- A. A positive linear trend
- B. A negative linear trend
- C. No trend
- D. A constant trend
9. Which of the following pairs of variables is LEAST likely to show a linear trend on a scatter plot?
- A. The number of tickets sold and the total revenue earned.
- B. A person's height and their favorite type of music.
- C. The speed of a car and the time it takes to travel 100 miles.
- D. The number of hours worked and the amount of money earned.
10. A gardener plants a sunflower seed and tracks its growth. A scatter plot is created with time on the $x$-axis and the sunflower's height on the $y$-axis. What kind of relationship would you expect to see?
- A. A positive trend
- B. A negative trend
- C. No relationship
- D. A random pattern