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.
   • An observational study: the class only measured what happened to the plants.
   • A sample survey: it asks a sample questions.
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?

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

3. Read this first

   Use this

   nobody was assigned.

4. 3.

   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?

   • An observational study: the students were already in their groups.
   • An experiment: two groups of students are compared on their catch distances.
   • A sample survey: it asks a sample questions.
5. 4.

   Tala measures the heights of 20 sunflowers already growing in shade and 20 already growing in sun in the school garden. Which kind of study is this?

   • An observational study: the sunflowers were already in shade or sun.
   • A sample survey: it asks a sample questions.
   • An experiment: two groups of sunflowers are compared on their heights.
6. 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?

   • It lets the result stand for all 800 students.
   • It shows what makes students read more.
   • Nothing: asking the first 40 at the door works as well.
7. 6.

   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. 7.

   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. 8.

   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. 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
11. 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