Consumers can purchase nonprescription medications at food stores, mass merchand

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 217 people chosen at random from the Indianapolis telephone directory. Here are the means and standard deviations of the performance scores for the sample.

(b) Give 99% confidence intervals for the mean performance for each type of store. (Round your answers to three decimal places.)

(c) Based on these confidence intervals, are you convinced that consumers think that pharmacies offer higher performance than the other types of stores? (In Chapter 12, we will study a statistical method for comparing means of several groups.)

Yes, the pharmacy interval is well above the others.

Yes, the mass merchandiser interval is well above the others.    

Yes, the food store interval is well below the others.

No, there is no clear evidence of a significant difference.

Store type x s Food stores 18.5 25.26 Mass merchandisers 32.4 33.04 Pharmacies 48.43 35.29

Explanation / Answer

for food stores:

std error =std deviation/(n)1/2 =1.715

and for 99% CI, z=2.5758

hence confidence interval for food stores: =mean +/- z*std deviation =14.083 ; 22.917

similarly confidence interval for mass marchendisers:

std error =std deviation/(n)1/2 =2.243

and for 99% CI, z=2.5758

hence confidence interval for food stores: =mean +/- z*std deviation =26.623 ; 38.177

for pharmacies"

std error =std deviation/(n)1/2 =2.396

and for 99% CI, z=2.5758

hence confidence interval for food stores: =mean +/- z*std deviation =42.259 ; 54.601

hence option B is correct

Yes, the pharmacy interval is well above the others.

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