AP Statistics · Topic 3.3

Random Sampling and Data Collection Practice

Part of Collecting Data.(DAT-2.B)

Practice questions

27

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Sample questions

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  1. Sample 1difficulty 1/5

    A high school principal wants to estimate the average number of hours per week that students spend on homework. She obtains a list of all 1,200 students from the registrar, assigns each student a number from 1 to 1,200, and uses a random number generator to select 60 distinct numbers. The students corresponding to those numbers are surveyed about their weekly homework hours.

    Population: 1,200 students Numbered 0001-1200 Random number generator SRS of 60 students Every group of 60 equally likely

    Which sampling method is being used?

    • A

      Cluster sample

    • B

      Stratified random sample

    • C

      Simple random sample

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    • D

      Systematic sample

    Why

    Every group of 60 students has an equal chance of being selected because the principal randomly draws 60 distinct numbers from the full roster. This is the defining property of a simple random sample.

  2. Sample 2difficulty 1/5

    A factory wants to estimate the proportion of defective bolts produced in a day. Bolts come off the assembly line one at a time. The quality engineer randomly selects a starting position between 1 and 50 and then inspects every 50th bolt thereafter throughout the shift.

    Bolts on assembly line Random start, then every 50th bolt Filled circles = inspected

    Which sampling method is being used?

    • A

      Cluster sample

    • B

      Systematic sample

      check_circle
    • C

      Convenience sample

    • D

      Simple random sample

    Why

    Selecting every kth element after a random start is a systematic sample. It is not an SRS because not all possible groups of bolts have equal probability of being chosen.

  3. Sample 3difficulty 1/5

    A school district has 80 elementary school classrooms, each containing about 25 students. Researchers want to estimate the proportion of students who eat breakfast at home. They randomly select 8 of the 80 classrooms and survey every student in those chosen classrooms.

    80 Classrooms (clusters) Shaded = 8 randomly chosen clusters Survey ALL students in those rooms ~200 students total

    Which sampling method is being used?

    • A

      Cluster sample

      check_circle
    • B

      Systematic sample

    • C

      Simple random sample

    • D

      Stratified random sample

    Why

    Classrooms (clusters) are randomly selected, and every student within the chosen clusters is surveyed. This is a cluster sample, distinguished from stratified sampling by sampling whole groups rather than within groups.

  4. Sample 4difficulty 1/5

    A teacher places all 28 of her students' names in a hat, mixes them, and draws 5 without replacement to form a focus group on classroom climate.

    28 names in a hat (well mixed) Draw 5 without replacement Focus group of 5 Each subset of 5 equally likely

    What sampling method is this?

    • A

      Cluster sample

    • B

      Simple random sample

      check_circle
    • C

      Stratified sample

    • D

      Convenience sample

    Why

    Drawing names from a thoroughly mixed hat without replacement gives every group of 5 students an equal chance of selection, the definition of an SRS.

  5. Sample 5difficulty 1/5

    The "population" in a survey is

    • A

      The group from which the sample is taken; the target group

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    • B

      100% always

    • C

      Only the people surveyed

    • D

      The sample itself

    Why

    Population = entire group of interest; sample = subset actually studied.