An advertising agency on the West Coast formulated a media advertising campaign for an online retailer and claims that its ads received “high approval” by at least 21% of adults with incomes over $50,000 per year. Suppose the online retailer wishes to test this claim. It surveys 883 adults with incomes exceeding $50,000 and finds that 168 give the ads “high approval.”
a. State the appropriate null and alternative hypotheses to be tested.
b. Based on an alpha level of 0.05, do the sample data provide evidence to reject the ad agency’s claim?