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.

   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?

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

   Ren plotted ten classmates' heights against the minutes each took to finish a paper maze. Which answer names the association and gives a good reason?

   • A positive association, because the right-most dot sits higher than the left-most dot.
   • A negative association, because a ruler line through the middle of the dots falls from left to right.
   • No association, because the left half and the right half of the dots spread over about the same y-values.
3. 3.

   Esme plotted the temperature at kickoff against the goals Esme's team scored in ten soccer games. Which answer names the association and gives a good reason?

   • A negative association, because the right-most dot sits lower than the left-most dot.
   • A positive association, because a ruler line through the middle of the dots rises from left to right.
   • No association, because the left half and the right half of the dots spread over about the same y-values.
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.

   Tala timed twelve bike rides of different lengths. On one ride, a strong wind pushed from behind the whole way. Which point is the outlier, written as (x, y)?

   (30, 50)
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.

   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
8. 8.

   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 B shows the stronger association, because its dots reach higher on the grid.
   • The two plots show the same strength, because each plot has 8 dots.
   • Plot B shows the stronger association, because its ruler line is steeper.
   • Plot A shows the stronger association, because its dots stay closer to its ruler line.
9. 9.

   Two groups rolled toy cars down ramps. The first group's cars had wobbly wheels, and Plot B is Ren's group. Which answer is right, with a good reason?

   • Plot B shows the stronger association, because its ruler line is steeper.
   • Plot B shows the stronger association, because its dots stay closer to its ruler line.
   • Plot A shows the stronger association, because its first dot sits higher.
   • The two plots show the same strength, because each plot has 8 dots.
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?

    • 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.
    • 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.