Interpreting the Trend Line

What is the equation of the line of best fit?

• y= 6x + 2

• y = -2x +6

What type of correlation does this graph have? Check ALL correct answers.

• positive

• negative

• linear

• non-linear

Answer explanation

A linear association doesn't have to be perfectly straight, just straight-ish.

Did you mark positive AND linear?

Which is the best estimate for the SLOPE of this trend line? Click the graph to see it.

• 50

• 75

• 0.02

• 2

Answer explanation

The slope is the ratio of rise to run for the line.

We also call slope the rate of change.

Which is the best estimate for the y-intercept of the trend line?

• 50

• 25

• 1

• 75

Answer explanation

The y-intercept is where the line crosses the y-axis.

Based on the slope and y-intercept of the trend line, which is the best estimate for the total dollars earned when time worked is 22 hours?

• $1350

• $2200

• $1650

• $1125

Answer explanation

y=50x+25 equation of trend line

y=50(22)+25 substitute in 22 hours for x

y=1125 simplify.

How should we describe this correlation? Check ALL correct answers.

• linear

• nonlinear

• one outlier

• no association

Answer explanation

This data HAS an association--it's just not straight-ish, so it's a non-linear association.

Did you see the outlier in the bottom left corner?

The scatter plot below shows the number of books read by students in Mrs. Hall’s English class and their final grades. Which statement represents the best description about the line of best fit?

• The more books students read, the lower their English grade.

• The more books students read, the higher their English grade.

• The fewer books students read, the higher their English grade. 

• No relationship exists between the number of books students read and their English grades. 

What type of relationship does this graph have?

• Positive

• Negative

• No Relationship

• Constant

Based on the scatter plot, which statement best describes the trend?

• As the daily temperature increases, the number of beach visitors increases.

• as the daily temperature decreases, the number of beach visitors increases.

• As the daily temperature increases, there is no change in the number of beach visitors

• As the daily temperature increases, the number of beach visitors decreases

In the scatter plot, does the image shows a "Line of Best Fit"?

• Yes

• No