Surveys, experiments and observational studies, and judging a report

Grade 11 Math Worksheet

Circle the best answer.

1. 1.

   Zee wants to know if music while studying changes quiz scores for the 60 students in a grade. Which plan answers the question best?

   • Let each student choose music or quiet, then compare scores.
   • Compare scores of students who already study with music and those who do not.
   • Assign the 60 students at random to music or quiet, then compare scores.
2. 2.

   Bo wants to know what percent of the school's 900 students walk to school. Which plan answers the question best?

   • Ask 9 students drawn at random from the full list.
   • Ask 90 students drawn at random from the full list of 900.
   • Ask the first 90 students who arrive at school in the morning.
3. 3.

   Esme wants to know the mean hours of sleep of the district's 3,000 seventh graders. Which plan answers the question best?

   • Ask 15 seventh graders drawn at random from the list.
   • Ask 150 seventh graders drawn at random from the district list.
   • Ask the 150 students in one school's early-morning club that meets daily.
4. 4.

   Of Jun's 80 classmates, those who chose to eat breakfast tend to score higher on morning quizzes. What does the study show?

   • It was an experiment, so breakfast is the cause.
   • Breakfast goes with higher scores; the study cannot show breakfast causes them.
   • Eating breakfast raises quiz scores.
5. 5.

   Of 120 students Kira studied, those who read for fun tend to know more vocabulary words. What does the study show?

   • It was an experiment, so reading for fun is the cause.
   • Reading for fun makes students learn more words.
   • Reading for fun goes with knowing more words; the study cannot show it causes that.
6. 6.

   Luz's class assigned 44 bean plants at random to plant food or plain water; the plant-food group grew taller. What does the study show?

   • The plant food likely made these bean plants grow taller.
   • It shows only a link; it cannot show plant food made the difference.
   • Plant food makes every kind of plant grow taller.
7. 7.

   Milo assigned 36 students at random to ruler-drop practice or none; the practice group caught the ruler sooner. What does the study show?

   • It shows only a link; it cannot show practice made the difference.
   • Practice makes every person in the world faster.
   • The practice likely made these students' catches faster.
8. 8.

   "Don't you agree the old library chairs are uncomfortable?" Sample: 200 names drawn at random from all 1,500 students. Noah checks the survey in the figure. What is its main problem?

   • 200 students is too few to tell anything.
   • The students were not drawn at random.
   • The wording pushes students toward yes.
   • Nothing: the sample was random, so the result is fair.
9. 9.

   "Should the school keep the fun, popular field day?" Sample: 150 names drawn at random from all 1,200 students. Pia checks the survey in the figure. What is its main problem?

   • Nothing: the sample was random, so the result is fair.
   • The wording pushes students toward yes.
   • 150 students is too few to tell anything.
   • The students were not drawn at random.
10. 10.

    "Do you recycle at home?" Sample: the 80 members of the school's green club. Tala checks the survey in the figure. What is its main problem?

    • 80 students is too few to tell anything.
    • Nothing: the question is fair, so the result is fair.
    • Green club members likely recycle more than other students.
    • The wording pushes students toward one answer.