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7th grade · Math · Unit 16 of 17

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.

Alaska content standards learning standard: 7.SP.1; 7.SP.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 Alaska

In the Alaska content standards, this is unit 16 of 17 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: Alaska Department of Education and Early Development

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

    In a random sample of 20 students, 4 play an instrument. About how many of the 240 students at the school play an instrument?

    • 68
    • 40
    • 192
    • 48

  2. Question 2

    You want to know how voters in a city feel about a new park. Which sample is most likely to represent the population?

    • 200 people at a park opening
    • 200 people who live next to the park
    • 200 voters picked at random from the city's voter list
    • the first 200 people who email the city

  3. Question 3

    A school asks 60 of its 900 students about field trips. What is the population?

    • all 900 students
    • the 60 students asked
    • the field trips
    • the teachers

  4. Question 4

    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

  5. Question 5

    You want to know which lunch students at a school like best. Which sample is most likely to represent the population?

    • the first 40 students in the lunch line for pizza
    • 40 students picked at random from the whole school's list
    • the 40 students in one Grade 8 class
    • the 40 students in the chess club

  6. Question 6

    One random sample has 20 people and another has 300. Which estimate of the population is likely to be closer?

    • The sample of 20
    • They will always be exactly the same
    • The sample of 300

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