AP Statistics · Topic 5.4

Biased and Unbiased Point Estimates Practice

Part of Sampling Distributions.(UNC-3.E)

Practice questions

9

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Sample questions

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  1. Sample 1difficulty 1/5

    Which symbol denotes the population standard deviation?

    • A

      σ̂

    • B

      σ_x̄

    • C

      s

    • D

      σ

      check_circle

    Why

    σ is the population standard deviation; s denotes the sample standard deviation.

  2. Sample 2difficulty 1/5

    A random sample of 50 voters is taken from a city, and 32 of them favor a new ordinance.

    Sample of 50 voters 32 favor / 50 sampled p̂ = 32/50 = 0.64

    The value 32/50 = 0.64 is best described as which of the following?

    • A

      A statistic, x̄

    • B

      A parameter, p

    • C

      A parameter, μ

    • D

      A statistic, p̂

      check_circle

    Why

    Because 0.64 was computed from a sample, it is a statistic — specifically the sample proportion p̂.

  3. Sample 3difficulty 1/5

    Which symbol denotes the population proportion?

    • A

      P_x̄

    • B

    • C

      p

      check_circle
    • D

      π̂

    Why

    p denotes the population proportion; p̂ is the sample proportion.

  4. Sample 4difficulty 2/5

    A statistic T is being evaluated as an estimator for a parameter θ.

    center at μ

    Which statement best describes an unbiased estimator?

    • A

      The mean of its sampling distribution equals the parameter being estimated.

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    • B

      Its sampling distribution is symmetric.

    • C

      Its standard deviation is small.

    • D

      It always equals the parameter.

    Why

    An estimator is unbiased when the mean of its sampling distribution equals the population parameter.

  5. Sample 5difficulty 2/5

    A researcher computes the average height of all 1,200 students at a high school and finds it to be 65.4 inches.

    Population vs Sample μ, σ, p Population x̄, s, p̂ Sample

    Which symbol best represents the value 65.4 inches?

    • A

    • B

      p

    • C

      μ

      check_circle
    • D

    Why

    Because every student in the population was measured, 65.4 inches is a parameter — the population mean μ.