Question 7.169

43. Abandoning Landlines. Refer to Exercise 39.

  1. Find the 5th and 95th percentiles of the sample proportions.
  2. Draw a graph showing the sampling distribution of , centered at , with the 5th and 95th percentiles, and the area of 0.90 under the curve between them shaded.
  3. Suppose only 2 of 36 phone users in a sample abandoned their landlines. Would this be considered an outlier? Explain your reasoning. (Hint: Use the Z-score method.)
  4. Determine which sample proportions would be considered outliers.

7.2.43

(a) 0.1312, 0.3688

(b)

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(c) For . Thus is considered moderately unusual. (d) Sample proportions between 0 and 0.0334 inclusive and between 0.4666 and 1 inclusive would be considered outliers.