Unit 5:Day 1

 Day 1.

Students will use the line of best fit to find equations of lines.

Line of best fit: a straight line that best represents the data on a scatter plot.
This line may pass through some of the points, none of the points, or all of the points, depending of how many points you have.

As shown here, there are equal points from the left and the right of the line.

Quiz # 1

Use the table that shows the number of goals Pierre scored playing hockey to answer problems 1–4.
1. Using the data from 2001 and 1997, find the slope of the line.
2. With your answer from problem 1 and the point (2000, 19), write
an equation for the line in slope-intercept form.



 Goals   Year
1997
            26                                                                                   
1998
              24
1999
             20
2000
            19
2001
               15

Answers: 1. m=-11/4, find the slope by rise/run. or mx+b.    Connect to points, then apply the formula, where m is the slope,x is the amount of intervals, and b is the y intercept.

                             

2. y=-11/4x+5519

3. The table shows Tisha’s height at various ages. Use the information to make a scatter plot, draw a best-fit line, and write an equation for the data.

Example

AAge

        Height in Inches

10

           57

11

           60

12

           62

13

           63

14

          66.5                                                        

15

           68

Answer: Select two points to find the slope.

x1 =15,y1=68,x2 =12,y2=62             y2-y1/x2-x1

The slope is 2. 

Use the slope-intercept form. 

Replace m with 2 and use any point. 

Solve for b. 

Replace m and b in the equation.

Video Explanation