9. Eighth-Grade Alcohol Use. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) reports on the proportion of eighth-graders who have used alcohol (Source: http://www.niaaa.nih.gov/publications). A random sample of 100 eighth-graders this year showed that 41 of them had used alcohol. Test whether the population proportion of eighth-graders who have used alcohol is less than 0.5, using level of significance .