Jean is trying to gauge the popularity of a proposal to change the city's one-way street to two - way streets. She polls 650 randomly selected individuals from the area to determine if they are in favor of the project. She finds that 280 respond in favor of the project. What s the 90% confidence interval for the proportion of the population who are in favor of the project?

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Business

Adison Williams

14 May, 06:47

Jean is trying to gauge the popularity of a proposal to change the city's one-way street to two - way streets. She polls 650 randomly selected individuals from the area to determine if they are in favor of the project. She finds that 280 respond in favor of the project. What s the 90% confidence interval for the proportion of the population who are in favor of the project?

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Richard Dougherty · Answer 1

(0.3989, 0.4627)

Explanation:

Given the information we are required to find the 90% confidence interval for the proportion of the population who are in favor of the project.

The z-value = 1.645, proportion = 280/650 = 0.4308

and the SE = sqrt (0.4308 * (1-0.4308) / 650).

Therefore the confidence interval = (0.4308 - 1.645*0.0194, 0.4308 + 1.645*0.0194). Which means that the answer is (0.3989, 0.4627)