Over one decade (1995–2005), the number of hip and knee replacement surgeries increased by 87%. Because the costs of hip and knee replacements are so expensive, private health-insurance and government-operated health-care plans have become more concerned. To get more information, random samples of people who had hip replacements in 1995 and in 2005 were drawn. From the files, the ages of the patients were recorded. Is there enough evidence to infer that the ages of people who require hip replacements are getting smaller?