The National Center for Health Statistics interviewed 5409 adult smokers in 2015, and 2636 of them said they had tried to quit smoking during the past year. Consider this to be a random sample. a) Find a 95% confidence interval for the proportion of smokers who have tried to quit within the past year. b) Find a 99% confidence interval for the proportion of smokers who have tried to quit within the past year. c) Someone claims that the proportion is less than 0.5. With what level of confidence can this statement be made? d) Find the sample size necessary for a 95% confidence interval to specify the proportion to within ±0.01. e) Find the sample size necessary for a 99% confidence interval to specify the proportion to within ±0.01.
The National Center for Health Statistics interviewed 5409 adult smokers in 2015, and 2636
of them said they had tried to quit smoking during the past year. Consider this to be a
random sample.
a) Find a 95% confidence interval for the proportion of smokers who have tried to quit
within the past year.
b) Find a 99% confidence interval for the proportion of smokers who have tried to quit
within the past year.
c) Someone claims that the proportion is less than 0.5. With what level of confidence can
this statement be made?
d) Find the sample size necessary for a 95% confidence interval to specify the proportion
to within ±0.01.
e) Find the sample size necessary for a 99% confidence interval to specify the proportion
to within ±0.01.
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