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.

   nobody was assigned. 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?

   • A sample survey: it asks a sample questions.
   • An experiment: two groups of sunflowers are compared on their heights.
   • An observational study: the sunflowers were already in shade or sun.
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 makes the groups alike, so a difference can be put down to the plant food.
   • It lets the result describe every bean plant in the world, even ones never in the study.
4. 4.

   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 shows what makes students read more.
   • It lets the result stand for all 800 students.
   • Nothing: asking the first 40 at the door works as well.
5. 5.

   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?

   • It shows what makes students recycle.
   • Nothing: asking the 50 students in the green club works as well.
   • It lets the result stand for all 600 students.
6. 6.

   400 dots (seventh graders); 50 circled, drawn at random, spread all over the plot. Jun draws 50 names at random from all 400 seventh graders and asks about sleep. Who can the result describe?

   • Only the 50 students asked
   • All 400 seventh graders at the school
   • Every student in the state
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?

   • Only the 90 who chose to answer; they may feel strongly
   • Every student in the country
   • 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.

    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