A labor economist wants to estimate, with confidence, the proportion of remote workers in the workforce. The economist wants the estimate to be accurate within of the true population proportion. What is the minimum sample size needed for this estimate?
Table of contents
- 1. Introduction to Statistics53m
- 2. Describing Data with Tables and Graphs2h 1m
- 3. Describing Data Numerically1h 48m
- 4. Probability2h 26m
- 5. Binomial Distribution & Discrete Random Variables2h 55m
- 6. Normal Distribution & Continuous Random Variables1h 48m
- 7. Sampling Distributions & Confidence Intervals: Mean2h 8m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 20m
- 9. Hypothesis Testing for One Sample2h 23m
- 10. Hypothesis Testing for Two Samples3h 25m
- 11. Correlation1h 6m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 30m
- 14. ANOVA1h 4m
8. Sampling Distributions & Confidence Intervals: Proportion
Confidence Intervals for Population Proportion
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Make a confidence interval for p given the following values.
p^=0.15,n=60,C=90%
A
(0.055,0.245)
B
(0.074,0.245)
C
(0.074,0.226)
D
(0.055,0.226)

1
Step 1: Identify the given values in the problem. Here, the sample proportion is \( \hat{p} = 0.15 \), the sample size is \( n = 60 \), and the confidence level is \( C = 90\% \).
Step 2: Calculate the standard error (SE) of the sample proportion using the formula \( SE = \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}} \). Substitute \( \hat{p} = 0.15 \) and \( n = 60 \) into the formula.
Step 3: Determine the critical value (z*) for a 90% confidence level. For a 90% confidence interval, the critical value corresponds to the z-score that leaves 5% in each tail of the standard normal distribution. Use a z-table or statistical software to find \( z^* \).
Step 4: Compute the margin of error (ME) using the formula \( ME = z^* \cdot SE \). Multiply the critical value \( z^* \) by the standard error \( SE \) calculated in Step 2.
Step 5: Construct the confidence interval using the formula \( \text{Confidence Interval} = \hat{p} \pm ME \). Subtract the margin of error from \( \hat{p} \) to find the lower bound and add the margin of error to \( \hat{p} \) to find the upper bound.
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