More prayer in school Refer to Exercise . Interpret the confidence level.
All samples to have confidence interval have population parameter.
It is given that for confidence interval, proportion is
Video games A Pew Research Center report on gamers and gaming
estimated that of U.S. adults play video games on a computer, TV, game console, or portable device such as a cell phone. This estimate was based on a random sample of U.S. adults. Construct and interpret a confidence interval for the proportion of all U.S. adults who play video games.
Power lines and cancer Does living near power lines cause leukemia in
children? The National Cancer Institute spent years and million gathering data on this question. The researchers compared children who had leukemia with who did not. They went into the homes and measured the magnetic fields in children’s bedrooms, in other rooms, and at the front door. They recorded facts about power lines near the family home and also near the mother’s residence when she was pregnant. Result: No association between leukemia and exposure to magnetic fields of the kind produced by power lines was found.
a. Was this an observational study or an experiment? Justify your answer.
b. Does this study prove that living near power lines doesn’t cause cancer? Explain your answer.
Explaining confidence The admissions director for a university found that is a confidence interval for the mean IQ score of all freshmen. Discuss whether each of the following explanations is correct, based on that information.
a. There is a probability that the interval from role="math" localid="1654200953396" contains .
b. There is a chance that the interval contains .
c. This interval was constructed using a method that produces intervals that capture the true mean in of all possible samples.
d. If we take many samples, about of them will contain the interval .
e. The probability that the interval captures is either or , but we don’t know which.
Running red lights A random digit dialing telephone survey of 880 drivers asked, “Recalling the last ten traffic lights you drove through, how many of them were red when you entered the intersections?” Of the 880 respondents, 171 admitted that at least one light had been red.37
a. Construct and interpret a 95% confidence interval for the population proportion.
b. Nonresponse is a practical problem for this survey—only 21.6% of calls that reached a live person were completed. Another practical problem is that people may not give truthful answers. What is the likely direction of the bias: Do you think more or fewer than 171 of the 880 respondents really ran a red light? Why? Are these sources of bias included in the margin of error?
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