Chapter 8: Q 12. (page 507)
More weight loss Refer to Exercise . Interpret the confidence level.
of all samples are havingconfidence interval that have true population parameter.
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Age and video games Refer to Exercise 41. The study also estimated that 67% of adults aged play video games, but only of adults aged and older play video games.
a. Explain why you do not have enough information to give confidence intervals for these two age groups separately.
b. Do you think a confidence interval for adults aged would have a larger or smaller margin of error than the estimate from Exercise 41? Explain your answer.
Election polling Gloria Chavez and Ronald Flynn are the candidates for mayor in a large city. We want to estimate the proportion p of all registered voters in the city who plan to vote for Chavez with confidence and a margin of error no greater than . How large a random sample do we need?
Shoes The AP Statistics class in Exercise 1 also asked an SRS of boys at their school how many pairs of shoes they have. A confidence interval for the true difference in the mean number of pairs of shoes for girls and
boys is .
a. Interpret the confidence interval.
b. Does the confidence interval give convincing evidence of a difference in the true mean number of pairs of shoes for boys and girls at the school? Explain your answer.
School vouchers A small pilot study estimated that of all American
adults agree that parents should be given vouchers that are good for education at any public or private school of their choice.
a. How large a random sample is required to obtain a margin of error of at most with confidence? Answer this question using the pilot studyโs result as the guessed value for
b. Answer the question in part (a) again, but this time use the conservative guess. By how much do the two sample sizes differ?
Age and September 11 Refer to Exercise 42. The study also reported that of
millennials included in their top-10 list and of baby boomers included .
a. Explain why you do not have enough information to give confidence intervals for
millennials and baby boomers separately.
b. Do you think a confidence interval for baby boomers would have a larger or smaller margin of error than the estimate from Exercise 42? Explain your answer.
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