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7th grade · Math · Unit 16 of 18

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.

Alabama Course of Study content standard: 7.10 · using a sample to draw conclusions 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 Alabama

In the Alabama Course of Study, this is unit 16 of 18 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: Alabama State Department of Education (ALSDE)

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?

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

  2. Question 2

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

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

  3. Question 3

    In a random sample of 40 students, 3 have a library card. About how many of the 520 students at the school have a library card?

    • 481
    • 39
    • 79
    • 30

  4. Question 4

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

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

  5. Question 5

    One random sample has 30 people and another has 300. Which estimate of the population is likely to be closer?

    • They will always be exactly the same
    • The sample of 30
    • The sample of 300

  6. Question 6

    In a random sample of 25 students, 2 have a library card. About how many of the 250 students at the school have a library card?

    • 20
    • 19
    • 230
    • 45

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