Use the following for the next 3 questions. I drink a lot of…

Use the following for the next 3 questions. I drink a lot of soft drinks so I want to test if soft drinks increase tooth probe depth to dangerous levels. According to the all-knowing ‘Wikipedia’, a tooth probe depth of more than 4mm is considered moderate periodontal disease.  I collect a sample of 49 people who drink a lot of soft drinks, and find them to have an average tooth pocket depth of 4.2mm and a sample standard deviation of 1mm.