Algebra 1 – U3 Day 12: Scatter plots and Best-Fit Lines
Data with two variables are called _________________________ data. A __________________ _______________ shows
the relationship between a set of data with two variables, graphed as ordered pairs on a coordinate plane.
Describe the type of correlation. Explain what the graph is showing.
Example 1: The table shows the largest vertical drops of nine roller coasters in the U.S. and the number
of years after 1988 that they were opened.
Years Since 1988
Vertical Drop (ft)
1
151
3
5
8
12
155 225 230 306
a) Make a scatter plot. Label the axes.
b) Draw a line of best fit.
c) Write an equation using 2 points from your best fit line.
d) Predict the vertical drop in a roller coaster built in 2018.
12
300
12
255
13
255
15
400
Example 2
The table shows the median age of females when they were first married.
Year
Age
1996
24.8
1997
25.0
1998
25.0
1999
25.1
2000
25.1
2001
25.1
2002
25.3
2003
25.3
2004
25.3
2005
25.5
2006
25.9
a) Make a scatter plot. Label the axes.
b) Draw a line of best fit.
c) Write an equation using 2 points from your best fit line.
d) Predict what the median age of females when they are first married will be in 2016.
e) Do you think the equation can give a reasonable estimate for the year 2056? Explain?