A researcher wishes to estimate, with 90% confidence, the proportion of adults w

Question

A researcher wishes to estimate, with 90% confidence, the proportion of adults who have high-speed Internet access. Her estimate must be accurate within 1% of the true proportion. a) Find the minimum sample size needed, using a prior study that found that 38% of the respondents said they have high-speed Internet access. b) No preliminary estimate is available. Find the minimum sample size needed. What is the minimum sample size needed using a prior study that found that 38% of the respondents said they have high-speed Internet access?

Explanation / Answer

a) here p=0.38

margin of error E =0.01

for 90% confidence ; z=1.6449

therefore sample size n=p(1-p)*(Z/E)2 =~6375

b) for no prior estimate p=0.5

therefore sample size n=p(1-p)*(Z/E)2 =~6764

please revert for any clarification required.

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