1. 6-7: Scatter Plots & Equations of Lines
Essential Question: What is the difference between a trend line and a line of best fit?

2. 6-7: Scatter Plots & Equations of Lines
Back in 1-5, we used scatter plots to determine how two sets of data are related (positive/negative/no correlation). Now, we can write the equations of the trend lines that we drew.

3. 6-7: Scatter Plots & Equations of Lines
Length and Wingspan of Hawks
Make a scatter plot of the data to the right. Draw a trend line and write its equation.
Use the equation to predict the wingspan of a hawk that is 28 in long.
Type of Hawk
Length (in)
Wing- span (in)
Cooper’s 21 36
Crane 41
Gray 18 38
Harris’s 24 46
Roadside 16 31
Broad- winged 19 39
Short- tailed 17 35
Swanson’s

4. 6-7: Scatter Plots & Equations of Lines
Length and Wingspan of Hawks
Step 1: Make a scatter plot and draw a trend line. Estimate two points ON THE LINE.
Type of Hawk
Length (in)
Wing- span (in)
Cooper’s 21 36
Crane 41
Gray 18 38
Harris’s 24 46
Roadside 16 31
Broad- winged 19 39
Short- tailed 17 35
Swanson’s
Wingspan (in)
Length (in)

5. 6-7: Scatter Plots & Equations of Lines
Step 2: Write an equation of the trend line
Points: (14, 30) and (22, 44)
Wingspan (in)
Step 3: Predict the wingspan of a hawk that is 28 in. long
y – 30 = 7/4 (28 – 14) Substitute 28 for x
y – 30 = 7/4 (14) Parenthesis
y – 30 = Multiply
y = Add 30 to each side
Length (in)

6. 6-7: Scatter Plots & Equations of Lines
Your Turn
Graph the data below and draw a trend line.
Find an equation for the trend line.
Estimate the number of Calories in a fast-food that has 14g of fat.
Calories and Fat in Selected Fast-Food Meals
Fat (g) 6 7 10 19 20 27 36
Calories
276
260
220
388
430
550
633

7. 6-7: Scatter Plots & Equations of Lines
Assignment
Worksheet #6-7
1 – 3 and 8 – 11 (all)