A national health organization warns that 30% of middle school students nationwide have been drunk. Concerned, a local health agency randomly and anonymously surveys 110 of the 1212 middle school students in its city. Only 21 of them report having been drunk.
a) What proportion of the sample reported having been drunk?
b) Does this mean that this city s youth are not drinking as much as the national data would indicate? Explain.
c) Create a 95% confidence interval for the proportion of the city s middle school students who have been drunk.
d) Is there any reason to believe that the national level of 30% is not true of the middle school students in this city?