Scatter Plots & Slopes

Scatterplots & Slopes

Remember: A function is when two variables are compared mathematically.

The X is what we change. The Y is what the result of that change is.

SO far we have been studying formulas for straight lines.

y

y

=

=

-1 x

/ 3 (

+

2 3

x ) 4

–

As we have seen, real life stuff NEVER follows a straight line!

Remember when we graphed how long it took to run? distance in feet

NOT a straight line! time in seconds

Too many different slopes!

We use a scatter plot graph to figure out if the two things are related or not.

Let’s look at the real life story of different people who practice for basketball season:

AVG. 23 23 12 8 15 20 4 POINTS HOURS 10 12 5 6 8 8 5 PER WEEK PRACTICE

6

12 20 10

7

13

AVG. POINTS

HOURS OF PRACTICE HOURS PER WEEK PRACTICE

23

23

12

8

15

20

4

6

12

20

14

AVG. POINTS

10

12

5

6

8

8

1

7

10

15

8

If…the you look at the graph, there is …The more practice hours… more points scored. a general trend… …

If it were a perfect line, what kind of slope would the line have? POSITIVE

HOURS OF PRACTICE

This scatter plot shows a POSITIVE The general direction of a scatter plot is CORRELATION called a TREND, or a CORRELATION.

HOURS OF PRACTICE

Sometimes you can draw a line that is close to all the points in a scatter plot.

This is called a LINE OF FIT …because it fits! DUUUUUUUUUUUUUUHHH!!!

CLASS PROJECT!!!!! Take your shoes off!