1. Scatter Plots and Equations of Lines
You can use scatter plots to:
The three scatter plots below show the types of relationships two sets of data may have.
Would you expect a positive correlation, a negative correlation, or no correlation between the two data sets? Why?
1. the age of a used car and the asking price of the car
2. the length of a baby at birth and the month in which the baby was born
a person’s height and their shoe size
This is only the top portion of the back of the flipbook. See next slide for the bottom portion.
look for trends in data

2. This is only the bottom portion of the back of the flipbook.
See previous slide for the top portion.
If you are given a scatter plot, or data that would create a scatter plot (as opposed to a linear model), you can’t make a perfect linear equation touching all of the points. Instead, you find a __________________________. This allows you to estimate and make predictions.
Steps: 1) 2) 3)
4. Use the scatter plot below. Assume the scales
on each axis are one unit per tick mark.
Which of the equations would most accurately
represent the line of best fit for the data?
y = -2x + 10
y = 2x + 10
y = -2x – 10
y = 2x - 10
line of best fit
Graph the data as a scatter plot.
Draw a trend line (centrally thru the data).
Write an equation of your trend line, or make predictions from it.
5. The scatter plot represents tips earned (in
dollars) and time worked (in hours).
Based on a linear model of the data, which is the best prediction for the amount of tips earned in 5 hours of work?
E. $2
F. $15
G. $23
H. $31