Consumers can purchase nonprescription medications at food stores, mass merchand
ID: 3052682 • Letter: C
Question
Consumers can purchase nonprescription medications at food stores, mass merchandise stores such as Target and Wal-Mart, or pharmacies. About 45% of consumers make such purchases at pharmacies. What accounts for the popularity of pharmacies, which often charge higher prices?
A study examined consumers' perceptions of overall performance of the three types of stores, using a long questionnaire that asked about such things as "neat and attractive store," "knowledgeable staff," and "assistance in choosing among various types of nonprescription medication." A performance score was based on 27 such questions. The subjects were 217people chosen at random from the Indianapolis telephone directory. Here are the means and standard deviations of the performance scores for the sample.
We do not know the population standard deviations, but a sample standard deviation s from so large a sample is usually close to ?. Use s in place of the unknown ? in this exercise.
(a) What population do you think the authors of the study want to draw conclusions about?
What population are you certain they can draw conclusions about?
(b) Give 99% confidence intervals for the mean performance for each type of store. (Round your answers to three decimal places.)
Explanation / Answer
(a) What population do you think the authors of the study want to draw conclusions about?
citizens of Indianapolis
What population are you certain they can draw conclusions about?
citizens of Indianapolispharmacies
(b)(1-alpha)*100% confidence interval for population mean=sample mean±t(alpha/2,n-1)*s/sqrt(n)
99% confidence interval for population mean=mean±t(0.01/2, 217-1)*s/sqrt(n)
for food store
(c) Yes, the pharmacy interval is well above the others.
n= 217 sample mean= 18.61 sd= 24.51Related Questions
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