Question

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 report having being drunk. is there any reason to believe that the national level of 30% is not true of the middle school students in this city?

Answer 1

The proportion of middle school students reported having been drunk is :

P = 21/110 = 0.191 = 19.10%

Using this proportion and by creating a 95% Confidence Interval, is the range of proportion is between:

11.7% and 26.4%

Therefore it is not true that 30% of middle school students have been drunk.