**For 1 and 2 you need to do all three steps--so, you'll likely need to do the work on a separate piece of paper.**
1. Check the conditions.
2. Show the formula and use the confidence interval.
3. Write an interpretation of your interval.
Then, try to think about the second part...how do changes in the sample size (n) and the critical value (z*) affect the width of our interval?
Enjoy!
Investigating Confidence Intervals: Follow Up
A survey of
approximately 4,200 high school students in the Midwest (at a meeting of the
American Public Health Association in Denver) showed that 19.8% of students
were “hypertexters” and 11.5% were “hypernetworkers.” “Hypertexting” is defined
as sending at least 120 messages per school day. While “hypernetworking” is
defined as spending at least 3 hours per school day on social networking sites.
1.
Create a 90% confidence interval for the
proportion of Midwest high school students who can be categorized as
“hypertexters.”
2.
Create a 99% confidence interval to estimate the
percent of Midwest high-school students who “hypernetwork.”
3.
Consider the equation for a one proportion z-interval. What two variables do we, as the
statisticians conducting the study, have
the ability to manipulate?
____________ and _____________
4.
How will changes in _______ affect the width of
the interval?
5.
How will changes in _______ affect the width of
the interval?
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