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According to Forbes, Creative Good, a New York based consultingfirm, claims that

ID: 2954850 • Letter: A

Question

According to Forbes, Creative Good, a New York based consultingfirm, claims that 40% of shoppers fail in their attempts topurchase merchandise online because web sites are too complex.Another consulting firm asked a random sample of 60 online shoppersto each test a different randomly selected e-commerce web site.Only 15 reported sufficient frustration with their sites to determaking a purchase.
a. What are the appropriate null and alternative hypotheses to testthe claim made by Creative Good?
b. Do the data provide sufficient evidence to support the claim?Use = .01.
c. Calculate and interpret the p-value for the test.

Explanation / Answer

Given n=60, phat=15/60=0.25 (a) The test hypothesis is Ho:p=0.4 Ha:p not equal 0.4 (b) Given =0.01, Z(0.005)=2.58 (check normal table) The test statistic is Z=(phat-p)/p*(1-p)/n =(0.25-0.4)/sqrt(0.4*0.6/60) =-2.37 Since Z=-2.37>-2.58, we do not reject Ho. (c) p-value=2*P(Z