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?

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

   Ari wants to know if a new plant food makes bean plants grow taller, using 40 bean plants. Which plan answers the question best?

   • Assign the 40 plants at random to plant food or plain water, then compare growth.
   • Compare growth of bean plants whose owners already use plant food with those that do not.
   • Let each plant's owner choose plant food or water, then compare growth.
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 the 150 students in one school's early-morning club that meets daily.
   • Ask 150 seventh graders drawn at random from the district list.
   • Ask 15 seventh graders drawn at random from the list.
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?

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

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

   • Practice makes every person in the world faster.
   • It shows only a link; it cannot show practice made the difference.
   • The practice likely made these students' catches faster.
7. 7.

   "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?

   • Nothing: the sample was random, so the result is fair.
   • The wording pushes students toward yes.
   • 200 students is too few to tell anything.
   • The students were not drawn at random.
8. 8.

   "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.
9. 9.

   "How many minutes did you read last night?" Sample: the 120 students at the library after school. Ren checks the survey in the figure. What is its main problem?

   • The wording pushes students toward one answer.
   • Students at the library may read more than others.
   • 120 students is too few to tell anything.
   • Nothing: the question is fair, so the result is fair.
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?

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