Scatterplots Line of Fit

Suppose data related to the AVERAGE Temperature outside (T) and the number of winter Coats (C) sold at a store is collected and graphed.

The LINE OF BEST FIT has the equation C = -3T + 150.

Use this equation to predict the number of coats sold when the average temperature outside is 20°.

• 40

• 75

• 90

• 115

Suppose a LINE OF BEST FIT passes through the points (4, 8) and (6, 2). The SLOPE of this line is . . .?

• -3

• -6

• 4

• 2

Tags

CCSS.8.EE.B.5

The Y-INTERCEPT of this line is . . .? (hint: find the equation in point-slope form first and then put it into slope-intercept form)

• 11

• 4

• 9

• 20

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.3

Using your slope from the previous question, give the equation for the line of best fit in point-slope form (choose 1 of the 2 points you used to find the slope)

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

• A

• B

• C

• D

Tags

CCSS.8.EE.B.5

Suppose the equation of the line of best fit for the scatterplot is y=-25x+170 Use the information to predict the remaining distance, when the bicyclist has traveled 3 hours.

• 95 km

• 98 km

• 2 hours

• Not enough information.

Tags

CCSS.HSF.LE.B.5

You plot these points (0,0.5), (1,2), (3,5), (6,7), (10, 8) and draw a scatter plot. If you use the points (2, 3) and (6,6) on the line of best fit to find the equation, which of the following is the equation of the line of best fit?

• y = x

• y = 0.75x + 1.5

• y = x+1

• y = 0.5x+3

What type of association does this graph have?

• positive 

• negative

• none

• all of the above

What is the purpose of a line of best fit?

• To go through every point

• To make predictions about the data

• To go through none of the points

• To tell you absolutely everything about a data set

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 pages would be in a book with 19 chapters. 

• 150 pages

• 170 pages

• 190 pages

• 210 pages