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?

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

   nobody was assigned. Ren measures the ruler-drop catch distances of 25 students who already play a ball sport and 25 who do not. Which kind of study is this?

   • A sample survey: it asks a sample questions.
   • An experiment: two groups of students are compared on their catch distances.
   • An observational study: the students were already in their groups.
4. 4.

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

   • 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.
   • Nothing: the class could pick the strongest plants for plant food.
5. 5.

   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 makes the groups alike, so a difference can be put down to the practice.
   • It lets the result describe every student in the country, even ones never in the study.
6. 6.

   600 dots (students); 50 circled by chance, spread all over the plot. Esme picks 50 of the school's 600 students at random to ask about recycling. What does the random pick do?

   • Nothing: asking the 50 students in the green club works as well.
   • It lets the result stand for all 600 students.
   • It shows what makes students recycle.
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?

   • Only those 40 students; the front of the line may not be typical
   • All 500 students at the school
   • 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?

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

   Pia's report graph starts its axis at 120, not 0. A bar shows 128 students who bike. How many units tall is that bar drawn above the axis start?

   8
10. 10.

    Tala's report graph starts its axis at 64, not 0. A bar shows 69 students who walk. How many units tall is that bar drawn above the axis start?

    5