Here's your quiz for today. Please write your answers on separate paper and hand this in before the end of class. If everyone finishes, you may work with a partner to finish up your multiple choice or work on your reading quiz. Both of these will be collected Monday.
Confidence Intervals Quiz (Due by the end of class; NO NOTES, NO PARTNERS) (28 points)
1.) A Rutgers University study released in 2002 found that many high-school students cheat on tests. The researchers surveyed a random sample of 4500 high school students nationwide; 74% of them said they had cheated at least once.
a.) Create a 90% confidence interval for the level of cheating among high-school students. (Don’t forget the conditions!) Show all of your work. (6 points)
b.) In a complete sentence, interpret your confidence interval from part a. (3 points)
c.) A teacher surveys his students and finds that 68% of students have cheated on a test. Does this value seem reasonable? Surprising? Explain your reasoning. (3 points)
d.) Suppose we sample 2,000 students and find that 67% have cheated. Calculate the margin of error. (3 points)
e.) It had been believed that 3 out of every 4 students had cheated on a test in 2000. Does the confidence interval above suggest that this percentage has fallen? Explain. (3 points)
f.) Explain what 90% confidence means IN THIS CONTEXT. (3 points)
g.) If we want to have a margin of error of only 3% and want 98% confidence, how large of a sample must be used? (5 points)
h.) What is the probability that our confidence interval contains the true proportion of students who have cheated? (2 points)
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