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Home Ownership An urban economist wishes to estimate the
Chapter 5, Problem 34AYU(choose chapter or problem)
An urban economist wishes to estimate the proportion of Americans who own their homes. What size sample should be obtained if he wishes the estimate to be within 0.02 with 90% confidence if
(a) he uses a 2010 estimate of 0.669 obtained from the U.S Census Bureau?
(b) he does not use any prior estimates?
Questions & Answers
QUESTION:
An urban economist wishes to estimate the proportion of Americans who own their homes. What size sample should be obtained if he wishes the estimate to be within 0.02 with 90% confidence if
(a) he uses a 2010 estimate of 0.669 obtained from the U.S Census Bureau?
(b) he does not use any prior estimates?
ANSWER:Step 1 of 2
We need to determine the size of the sample should be obtained if he wishes the estimate to be within 0.02 with 90% confidence if
(a) The sample size required to obtain a confidence interval for with a margin of error is given by
\(n=\widehat{p}(1-\widehat{p})\left[\frac{Z \alpha / 2}{E}\right]^{2}\)
Using \(\widehat{p}=0.669\), E = 0.02 and the Z-score corresponding to 90% confidence level is 1.645.
\(\begin{aligned} n & =0.669(1-0.669)\left[\frac{1.645}{0.02}\right]^{2} \\ n & =0.669(0.331)\left[\frac{1.645}{0.02}\right]^{2} \\ \mathrm{n} & =1498.0486 \approx 1499 \end{aligned}\)