Stat 311 Spring 2015
The Department of Statistics estimates that 30% of students at the University of Washington will have taken STAT 311 by
the time they graduate.
You believe it is less than 30%, and decide to take a survey of graduating seniors to estimate
the true proportion.
Your friend gets you a list of the graduating seniors and their email addresses, and you randomly
select a sample of n=100, email them, and ask them to report on a Catalyst survey whether they have taken STAT 311:
25 of the 100 seniors report that they have.
Set up a 90% CI for the estimated proportion of seniors who have taken STAT 311.
With plug-in values:
State the null and the general alternative hypotheses. What is the approximate distribution of the sample
proportion under the null hypothesis?
(Specify the form of the null distribution, the mean and the standard
deviation, you do not need to solve for numerical value of the standard deviation).
Regardless of your answers above, set up a hypothesis test of
= 0.30 vs.
Test statistic in symbols
Test statistic with values
Is this a