Subscribe

7th grade · Math · Unit 15 of 16

Samples & Populations

Random samples and estimates

What your child practices

Telling a sample from a population, choosing a fair random sample, and using sample results to estimate for a whole population.

Arizona Academic Standards learning standard: 7.SP.A.1; 7.SP.A.2 · using random samples to draw inferences about a population

How we explain it

Children can open this short lesson before they practice.

  1. The population is the whole group. A sample is part of it.
  2. A random sample gives everyone an equal chance to be picked.
  3. Use the sample's fraction to estimate for the population.

Example: In a random sample of 50 students, 10 bike to school. About how many of 400 students bike? 10/50 = 1/5. 1/5 of 400 = 80. Answer: About 80

Samples & Populations in Arizona

In the Arizona Academic Standards, this is unit 15 of 16 in 7th grade Math, after Angle Relationships and before Scale Drawings.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Arizona Department of Education

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A park ranger tags 30 of the deer in a park to study them. What is the population?

    • all the deer in the park
    • the trees in the park
    • the 30 tagged deer
    • the park rangers

  2. Question 2

    In a random sample of 40 students, 29 have a library card. About how many of the 280 students at the school have a library card?

    • 77
    • 243
    • 290
    • 203

  3. Question 3

    You want to know how many hours teens in a town spend online. Which sample is most likely to represent the population?

    • 100 teens chosen at random from the town's high schools
    • 100 teens at a video game store
    • the 100 teens who answer an online poll
    • 100 members of the town's running club

  4. Question 4

    One random sample has 20 people and another has 200. Which estimate of the population is likely to be closer?

    • The sample of 200
    • They will always be exactly the same
    • The sample of 20

  5. Question 5

    A park ranger tags 30 of the deer in a park to study them. What is the population?

    • the park rangers
    • the 30 tagged deer
    • all the deer in the park
    • the trees in the park

  6. Question 6

    One random sample has 30 people and another has 200. Which estimate of the population is likely to be closer?

    • They will always be exactly the same
    • The sample of 200
    • The sample of 30

More 7th grade