SOLUTION: Based on a study conducted last year, the incidence of heavy drinking among teenagers was 15%. You are in charge of monitoring this rate and conducted the annual survey. Of the

Question 918679: Based on a study conducted last year, the incidence of heavy
drinking among teenagers was 15%. You are in charge of monitoring
this rate and conducted the annual survey. Of the 234 teenagers in
the survey, 40 of them were heavy drinkers. If you want to know if the
incidence rate has changed
a) What are the null and alternate hypotheses?
b) What is the test statistic to be used?
c) Using a 5% significance level, can we conclude that the incidence
rate has changed?
d) What could be other reasons for a statistically significant reason if
there is not truly one?

Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
Ho: p = 0.15 claim
Ha: p ≠ .15

-----------------------------------------
sample proportion = p-hat = 40/234 = 0.17
---
test stat:: z(0.17) = (0.17-0.15)/sqrt[0.15*0.85/234] = .02 /.0233 = .8568
-----
5% significance level, critical value = � 1.96
---------------------
Conclusiion:
Since .8568 < 1.96, accept the average of 15%.
The test results have not shown sufficient evidence to support it has changed.

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