33% of 515 eligible voters living in a particular city said they do not approve of the job the mayor is doing. In total, there are 29,352 eligible voters in the city. Given a 95% confidence level with a z-score of 1.96, which statement is most reasonable?(1 point)

Responses

Between 8,512 – 10,860 eligible voters do not support the mayor.
Between 8,512 – 10,860 eligible voters do not support the mayor.

Between 28,837 – 29,867 eligible voters do not support the mayor.
Between 28,837 – 29,867 eligible voters do not support the mayor.

About 1,891 eligible voters do not support the mayor.
About 1,891 eligible voters do not support the mayor.

Between 149 – 191 eligible voters do not support the mayor.

1 answer

To find the number of eligible voters who do not approve of the mayor, we need to calculate the sample proportion and then estimate the confidence interval for the population proportion.

  1. Calculate the proportion of disapproval among the sample:

    • Sample size \( n = 515 \)
    • Proportion of disapproval \( \hat{p} = 0.33 \)
  2. Calculate the number of voters who do not approve from the sample:

    • Number of voters who do not approve in the sample \( = 0.33 \times 515 \approx 173.95 \)
    • Rounding gives us approximately \( 174 \) voters in the sample.
  3. Calculate the standard deviation of the sample proportion: \[ \text{Standard deviation (SD)} = \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}} = \sqrt{\frac{0.33 \times (1 - 0.33)}{515}} \approx \sqrt{\frac{0.33 \times 0.67}{515}} \approx 0.0244 \]

  4. Calculate the confidence interval:

    • For a 95% confidence level, we use the z-score of \( 1.96 \).
    • Standard error (SE) = \( \text{SD} \approx 0.0244 \)
    • The margin of error (ME) = \( z \times \text{SE} = 1.96 \times 0.0244 \approx 0.0479 \)
  5. Calculate the confidence interval for the proportion:

    • Lower limit: \( \hat{p} - \text{ME} = 0.33 - 0.0479 \approx 0.2821 \)
    • Upper limit: \( \hat{p} + \text{ME} = 0.33 + 0.0479 \approx 0.3779 \)
  6. Convert the proportion confidence interval to the population:

    • Population size \( N = 29,352 \)
    • Lower limit for the number of voters: \( 0.2821 \times 29352 \approx 8286 \)
    • Upper limit for the number of voters: \( 0.3779 \times 29352 \approx 11056 \)

Thus, based on our calculations, we estimate that the number of eligible voters who do not support the mayor lies between approximately \( 8,286 \) and \( 11,056 \).

Among the response options provided, the closest reasonable statement is:

Between 8,512 – 10,860 eligible voters do not support the mayor.