Grossmont College Online Medical Information, Alcohol Consumption & Cigarette Smoking Discussion Estimating a Population Proportion discussion first one

Grossmont College Online Medical Information, Alcohol Consumption & Cigarette Smoking Discussion Estimating a Population Proportion discussion

first one
Prompt

Harris Interactive® conducted a poll of American adults in August of 2011 to study the use of online medical information. Of the 1,019 randomly chosen adults, 60% had used the Internet within the past month to obtain medical information.

Use the results of this survey to create an approximate 95% confidence interval estimate for the percentage of all American adults who have used the Internet to obtain medical information in the past month.
Calculate the 90% confidence interval.
Which confidence interval has the smaller margin of error? Why does this make sense?
Which confidence interval is more likely to contain the true percentage of all American adults who have used the Internet to obtain medical information in the past month? Why do you think so?
second one
Prompt

Recall the use of data from the National Health Survey to estimate behaviors such as alcohol consumption, cigarette smoking, and hours of sleep for all U.S. adults. In the 2005-2007 report, they estimated that 30% of all current smokers started smoking before the age of 16.

Suppose that we randomly select 100 U.S. adults who are smokers and find that 25% of this sample started smoking before the age of 16. Is this much error surprising? Find the probability that a sample proportion will be an over- or underestimate of the parameter by more than 5%.