The National Institutes of Health funded a study of a random sample of 856 people age 71 and older in the United States. They found that $9.7 \%$ of these people suffer from Alzheimer's Disease.
a. Identify the population of interest in this study.
b. Is .097 (the decimal version of $9.7 \%$ ) a parameter or a statistic? What symbol do you use to represent it?
c. Determine a 95\% confidence interval for the proportion of elderly Americans who have Alzheimer's disease.
d. Check and comment on whether the technical conditions required for this confidence interval are satisfied.
e. If you were to determine instead a $90 \% \mathrm{CI}$, how would it differ and how would it be similar to the result in part $\mathrm{c}$ ? (Do not bother to do the calculations.)
f. Determine how many people would have to be studied in a new sample if you want to estimate the population proportion to within $\pm$.02 with $99 \%$ confidence. (Use the result of the current sample in your determination of the new sample size.)

Question

Quizplus · Accepted Answer

The Answer of The National Institutes of Health funded a study of a random sample of 856 people age 71 and older in the United States. They found that $9.7 \%$ of these people suffer from Alzheimer's Disease.
a. Identify the population of interest in this study.
b. Is .097 (the decimal version of $9.7 \%$ ) a parameter or a statistic? What symbol do you use to represent it?
c. Determine a 95\% confidence interval for the proportion of elderly Americans who have Alzheimer's disease.
d. Check and comment on whether the technical conditions required for this confidence interval are satisfied.
e. If you were to determine instead a $90 \% \mathrm{CI}$, how would it differ and how would it be similar to the result in part $\mathrm{c}$ ? (Do not bother to do the calculations.)
f. Determine how many people would have to be studied in a new sample if you want to estimate the population proportion to within $\pm$.02 with $99 \%$ confidence. (Use the result of the current sample in your determination of the new sample size.)

The National Institutes of Health Funded a Study of a Random