Sampling Distributions for Sample Means

AP Statistics· difficulty 3/5

Cholesterol level has μ = 200 mg/dL, σ = 30. n = 25 people sampled.

Approximately, what is P(195 < x̄ < 210)?

  • A

    ≈ 0.7501

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  • B

    ≈ 0.3413

  • C

    ≈ 0.5000

  • D

    ≈ 0.9544

Explanation

σ_x̄ = 30/√25 = 6. z₁ = (195−200)/6 ≈ −0.83; z₂ = (210−200)/6 ≈ 1.67. P ≈ 0.9525 − 0.2033 ≈ 0.749.

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