Scatter Plots and Line of Best FIt

Scatter Plots and Line of Best FIt

Scatter Plot is

a type of graph to display data.

Three Types of Correlation

• Positive

• Negative

• No correlation

Multiple Choice

What type of correlation does this scatter plot show?

• positive

• negative

• no correlation

• nonlinear association

Multiple Choice

What type of correlation does this graph have?

• positive

• negative

• none

• all of the above

Multiple Choice

What type of correlation does this graph have?

• Negative

• no association

• positive

Multiple Choice

What type of correlation does this scatterplot have?

• Positive association

• Negative association

• No association

Line of Best Fit

• line through a scatter plot of data points that best expresses the relationship between those points. 

• can use the line of best fit to predict what could happen

• The line of best fit should be in the middle of the points

Multiple Choice

Which of the following lines represents the line of best fit for the scatter plot?

• A
• B
• C
• D

Multiple Choice

Which line is the best line of best fit?

• a

• b

• c

• i don't see any lines

Multiple Choice

Is this line an accurate line estimate of best fit for the data?

• Yes

• No

Multiple Choice

What is a line of best fit used for?

• To make predictions
• To make the graph look pretty
• To connect the points
• To make it look like you know what you are doing

Using Line of Best Fit to Make Predictions

• Based on the line of best fit

• how many points did someone who player 8 minutes score?

Multiple Choice

A small theme park is trying to determine the number of guests they should expect on a weekend, based on the temperature outside.  Based on the trend line, about how many guests should be expected if the temperature is around 80°?

• 8,300
• 8
• 7,300
• 9,300

Multiple Choice

The scatter plot shows the relationship between the number of chapters and the total number of pages for several books.  Use the trend line to predict how many chapters would be in a book with 180 pages. 

• 12 chapters
• 15 chapters
• 18 chapters
• 21 chapters

Writing an equation for the line of best fit.

• Find the y intercept It is your b.

      

  
  

• Find the slope. It is your m.

  
  

• Plug it into y =mx + b

  
  

• b = 7

• m = -4/7

• y = -4/7x + 7

• Now predict what happens when x = 7, what does y =?

Multiple Choice

The graph above shows a line of best fit for data collected on the distance bicyclists have remaining in relation to the amount of time they have been riding.  What is the equation of the line of best fit?

• y = -25x + 170
• y = 25x + 170
• y = -(5/8) x + 170
• y = (5/8) x + 170

Multiple Choice

The graph shows a line of best fit for data collected on the price of a unit in relation to the number of units sold.  What is the equation of the line of best fit?

• y = - (1/2) x + 10
• y = - (1/50) x + 40
• y = - (1/2) x + 40
• y = - (1/50) x + 10

Multiple Choice

The graph shows a line of best fit for data collected on the amount of income earned by lawn companies in relation to the number of yards mowed.  What is the equation of the line of best fit?

• y = (3/2) x
• y = 30x
• y = 30x + 300
• y = (3/2)x + 300

Multiple Choice

The graph  shows a line of best fit for the data collected on the amount of cell phone bills in relation to the number of minutes used.  What is the equation of the line of best fit.

• y = (1/2) x + 3
• y = (1/2) x + 15
• y = (1/40) x 
• y = (1/40) x + 15

Writing an equation using your calculator

• Stat Enter Input x and L1 and y as L2

• Stat arrow to calc then 4

• 
  

• 
  

Multiple Choice

The table shown is comparing a person's foot length to their height in cm. Calculate a line of best fit.

• f(x) = 25.05x + 5.57
• f(x) = 5.57x + 25.05
• f(x) = -5.57x + 25.05
• f(x) = 5.57x - 25.05