Surveys, experiments and observational studies, and judging a report

Answer Key - Grade 11 Math Worksheet - Building Confidence

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

1. 1.

   Noah's class assigns 30 bean plants at random: 15 get plant food and 15 get plain water. Then the class measures their growth. Which kind of study is this?

   • A sample survey: it asks a sample questions.
   • An observational study: the class only measured what happened to the plants.
   • An experiment: the class chose, at random, which plants got plant food.
2. 2.

   Pia's class flips a coin for each of 24 paper airplanes to give it long or short wings. Then the class measures every flight. Which kind of study is this?

   • An observational study: the class only measured what happened to the planes.
   • A sample survey: it asks a sample questions.
   • An experiment: the class chose, by coin flip, which planes got long wings.
3. 3.

   Zee's class assigns 30 bean plants at random to plant food or plain water. What does the random assignment do?

   • Nothing: the class could pick the strongest plants for plant food.
   • It lets the result describe every bean plant in the world, even ones never in the study.
   • It makes the groups alike, so a difference can be put down to the plant food.
4. 4.

   Ari assigns 20 students at random to practice a ruler-drop test or not practice. What does the random assignment do?

   • Nothing: Ari could pick the quickest students to practice.
   • It lets the result describe every student in the country, even ones never in the study.
   • It makes the groups alike, so a difference can be put down to the practice.
5. 5.

   800 dots (students); 40 circled by chance, spread all over the plot. Bo picks 40 of the school's 800 students at random to ask about reading. What does the random pick do?

   • Nothing: asking the first 40 at the door works as well.
   • It shows what makes students read more.
   • It lets the result stand for all 800 students.
6. 6.

   900 dots (students); 60 circled, drawn at random, spread all over the plot. Kira draws 60 names at random from all 900 students and asks about recycling. Who can the result describe?

   • Only the 60 students asked
   • Every student in the country
   • All 900 students at the school
7. 7.

   500 dots (students); the 40 circled all sit in one corner, the front of the lunch line. Luz asks the first 40 of the school's 500 students in the lunch line if lunch should be longer. Who can the result describe?

   • All 500 students at the school
   • Only those 40 students; the front of the line may not be typical
   • Every student in the state
8. 8.

   700 dots (students); the 90 circled are the ones who chose to answer, bunched together. All 700 students could answer Milo's online poll about a later start; 90 chose to answer. Who can the result describe?

   • Only the 90 who chose to answer; they may feel strongly
   • All 700 students at the school
   • Every student in the country
9. 9.

   Noah's report graph starts its axis at 80, not 0. A bar shows 86 votes for a class pet. How many units tall is that bar drawn above the axis start?

   6
10. 10.

    Ren's report graph starts its axis at 30, not 0. A bar shows 37 books returned late. How many units tall is that bar drawn above the axis start?

    7