Scatter Plots

Samples of students in each of the U.S. states periodically take part in a large-scale assessment called the National Assessment of Educational Progress (NAEP). The table below shows the percent of students in the northeastern states (as defined by the U.S. Census Bureau) who answered Problems 7 and 15 correctly on the 2011 eighth-grade test. How many different points will be located on a scatter plot of this data?

• 8

• 9

• 27

• 58

Answer explanation

Although there are nine states in our table, two of the states (New Hampshire and Rhode Island) share the same data point (29, 52), so there will only be 8 data points on a scatter plot.

The scatter plot shows the mean (average) percent of sunshine during the year and the mean amount of precipitation in inches per year for the states in the United States. Where on the graph are the states that have a large amount of precipitation and a small percent of sunshine?

• The lower right-hand corner of the scatter plot.

• The top left-hand corner of the scatter plot.

• The middle of the scatter plot.

At a dinner party, every person shakes hands with every other person present. The number of handshakes that take place for a given number of guests is represented by the scatter plot. Describe the scatter plot.

• There is no correlation with the data.

• The data has a negative relationship.

• The data has a positive, linear relationship.

• The data has a positive, non-linear relationship.

Answer explanation

The trend is increasing, but it is not linear. As the number of people increases, the number of handshakes also increases. It does not increase at a constant rate.

The red line represents the line of best fit for the scatter plot. How many ice cream sales are expected if the temperature is 90°?

• 55

• 0

• 103

• 100

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

What is the equation of the line of best fit

• y= -2x + 10

• y= 10x+ 2

• y=2x+10

• y= 10

If Joe worked 30 hours, how much is he expected to earn?

• $600

• $200

• $1000

• $800

Which scatter plot shows a linear relationship between x and y?

• Graph A

• Graph B

• Graph C

• Graph D

What type of correlation does this graph have?

• positive

• negative

• none

• all of the above

Label the type of association shown by the scatter plot as positive, negative or none.

• positive

• negative

• none