41. Health Care Costs. The U.S. Agency for Healthcare Research and Quality (www.ahrq.gov) reports that, in 2010, the mean cost of a stay in the hospital for American women ages 18–44 was $15,200. A recent random sample of 400 hospital stays of women ages 18–44 showed a mean cost of $16,000, with a standard deviation of $5000. Test whether the population mean cost has increased since 2010, using level of significance .
9.4.41
Critical-value method: . . Reject if . . Since is , the conclusion is reject . There is evidence at the 0.05 level of significance that the population mean cost of a stay in the hospital for women aged 18–44 is greater than $15,200. Therefore we can conclude at level of significance 0.05 that the population mean cost of a stay in the hospital for American women aged 18–24 has increased since 2010. method: . Reject if the . . . Since the is , the conclusion is reject . There is evidence at the 0.05 level of significance that the population mean cost of a stay in the hospital for women aged 18–44 is greater than $15,200. Therefore we can conclude at level of significance 0.05 that the population mean cost of a stay in the hospital for American women aged 18-24 has increased since 2010.