A university health services physician is concerned about how much sleep freshman are getting. She asked a simple random sample of 100 students if they got at least 8 hours of sleep the previous night. then she constructs a 90% confidence interval for the true proportion of all freshman college students who got at least 8 hours of sleep the previous night. Explain what would happen to the width of the interval if the sample size would decrease to 25 students

A political scientist claims that 38% of first-year college students characterize themselves as being “moderate” or “middle of the road” as far as their political affiliation is concerned.   Believing this claimed value is too high, you survey a random sample of 400 first-year college students and find that 120 characterize themselves as being “moderate” or “middle of the road.”    Based on this information, what will the test statistic be? Choose the answer below that is closest to what you calculate, and try not to do a lot of rounding until you get to the very end of your calculations.   1. -0.3 2. -1.2 3. -2.6 4. -3.3 5. None of the other answer options are correct because the test statistic should be positive, not negative.

In a sample of 400 Canadians, 220 say they would rather retire in the US than in Canada. Calculate the 95% confidence interval for the true proportion of Canadians who would rather retire in the US.

Wildlife biologists inspect 180 deer taken by hunters and find 36 of them carrying Lyme disease ticks. Calculate a 95% confidence interval for the proportion of deer that carry Lyme disease ticks.

Of 130 adults selected randomly from one town, 25 of them smoke. Construct a 99% confidence interval for the true percentage of all adults in the town that smoke.

A dowser has correctly located water for a well 1 out of 2 times in Jones County. In Jones County, someone who is just guessing has a 40% chance of locating water for a well. Does this sample provide sufficient evidence that the dowser can locate water and is not just guessing?

A poll showed that 40 out of 200 randomly chosen graduates of California medical schools last year intended to specialize in family practice. What is the width of a 95 percent confidence interval for the proportion that plan to specialize in family practice?

Public Policy Polling recently conducted a survey asking adults across the U.S. about music preferences. When asked, 80 of the 571 participants admitted that they have illegally downloaded music. Without performing any calculations, describe how the confidence interval would change if the confidence level changed from 99% to 90%.