Scatter plots: patterns of association

Answer Key - Grade 8 Math Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Noah's music club plotted minutes of guitar practice a day against chord changes made in one minute. Which answer names the association and gives a good reason?

   • A positive association, because a ruler line through the middle of the dots rises from left to right.
   • No association, because the dots do not all lie exactly on one line.
   • No association, because 10 dots are too few to show a pattern.
   • A negative association, because a ruler line through the middle of the dots rises from left to right.
2. 2.

   Pia's running club timed one lap each week of training and plotted the results. The club's cheer got louder every week. Which answer names the association and gives a good reason?

   • No association, because the dots do not all lie exactly on one line.
   • No association, because 10 dots are too few to show a pattern.
   • A negative association, because a ruler line through the middle of the dots falls from left to right.
   • A positive association, because a ruler line through the middle of the dots falls from left to right.
3. 3.

   Kira put a cup of juice in the freezer to make ice pops and checked its temperature every ten minutes. Which sentence describes the pattern of the dots?

   • No association: the dots tend to show no clear pattern.
   • A linear association: the dots tend to stay near one straight ruler line, going down steadily.
   • A nonlinear association: the dots tend to follow a curve, not one straight line.
4. 4.

   Milo's class counted the pencils left in the class box each week. One week, a helper found a lost bag of pencils. Which point is the outlier, written as (x, y)?

   (8, 88)
5. 5.

   Kira measured a tomato plant every week for twelve weeks. One week, the ruler slipped. Which point is the outlier, written as (x, y)?

   (6, 30)
6. 6.

   Jun's class survey plotted minutes of screen time a day against minutes spent outside. One dot is an outlier. How many dots are in the cluster with more screen time?

   7
7. 7.

   At the harbor, Zee measured sailboat lengths and mast heights. One dot is an outlier. How many boats are in the cluster of bigger boats?

   6
8. 8.

   In the park, Luz measured trunk widths and tree heights. One dot is an outlier. How many trees are in the cluster of thinner trees?

   6
9. 9.

   Two classes grew bean plants and plotted days against height. Plot A is Ari's class. Which answer is right, with a good reason?

   • Plot A shows the stronger association, because its dots stay closer to its ruler line.
   • Plot B shows the stronger association, because its ruler line is steeper.
   • The two plots show the same strength, because each plot has 8 dots.
   • Plot B shows the stronger association, because its dots reach higher on the grid.
10. 10.

    Milo flew big kites (Plot A) and small kites (Plot B) and plotted wind speed against kite height. Which answer is right, with a good reason?

    • The two plots show the same strength, because each plot has 8 dots.
    • Plot A shows the stronger association, because its dots reach higher on the grid.
    • Plot B shows the stronger association, because its dots stay closer to its ruler line.
    • Plot A shows the stronger association, because its ruler line is steeper and climbs higher.