Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals

Answered question

2021-12-16

Construct 90% and 95% confidence intervals for the population proportion. Interpret the results and compare the widths of the confidence intervals. In a survey of 2149 U.S. adults in a recent year, 1241 made a New Year's resolution to eat healthier.

 

Answer & Explanation

nick1337

nick1337

Expert2023-04-21Added 777 answers

To construct a confidence interval for the population proportion, we use the formula:

  CI=p±zα2p(1-p)n

where:
  CI = Confidence Interval
  p = sample proportion
  zα2 = z-score associated with the level of confidence
  n = sample size

First, we calculate the sample proportion:

  p=12412149=0.5767

For a 90% confidence interval, the z-score is:

  zα2=1.645

Plugging in the values, we get:

  CI=0.5767±1.6450.5767(1-0.5767)2149
     0.54760.6058

Therefore, we are 90% confident that the true proportion of U.S. adults who made a New Year's resolution to eat healthier is between 0.5476 and 0.6058.

For a 95% confidence interval, the z-score is:

  zα2=1.96

Plugging in the values, we get:

  CI=0.5767±1.960.5767(1-0.5767)2149
     0.5383 to 0.6151

Therefore, we are 95% confident that the true proportion of U.S. adults who made a New Year's resolution to eat healthier is between 0.5383 and 0.6151.

Comparing the widths of the confidence intervals, we can see that the 95% confidence interval is wider than the 90% confidence interval. This is because a higher level of confidence requires a larger range of possible values to be included in the interval, which results in a wider interval. However, the wider interval also gives us more certainty about the true population proportion.

Do you have a similar question?

Recalculate according to your conditions!

New Questions in High school statistics

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?