Question

A researcher wishes to estimate, with 95% confidence, the population proportion of motor vehicle fatalities that were caused by alcohol-impaired driving. His estimate must be accurate within 2% of the population proportion. (a) No preliminary estimate is available. Find the minimum sample size needed. (b) Find the minimum sample size needed, using a prior study that found that 22% of motor vehicle fatalities that were caused by alcohol-impaired driving. (c) Compare the results from parts (a) and (b). (a) What is the minimum sample size needed assuming that no prior information is available? (Round up to the nearest whole number as needed.) (b) What is the minimum sample size needed using a prior study that found that 22% of motor vehicle fatalities that were caused by alcohol-impaired driving? (Round up to the nearest whole number as needed.) (c) How do the results from (a) and (b) compare? A. Having an estimate of the population proportion reduces the minimum sample size needed. B. Having an estimate of the population proportion has no effect on the minimum sample size needed. C. Having an estimate of the population proportion raises the minimum sample size needed.

          A researcher wishes to estimate, with 95% confidence, the population proportion of motor vehicle fatalities that were caused by alcohol-impaired driving. His estimate must be accurate within 2% of the population proportion.
(a) No preliminary estimate is available. Find the minimum sample size needed.
(b) Find the minimum sample size needed, using a prior study that found that 22% of motor vehicle fatalities that were caused by alcohol-impaired driving.
(c) Compare the results from parts (a) and (b).
(a) What is the minimum sample size needed assuming that no prior information is available?
(Round up to the nearest whole number as needed.)
(b) What is the minimum sample size needed using a prior study that found that 22% of motor vehicle fatalities that were caused by alcohol-impaired driving?
(Round up to the nearest whole number as needed.)
(c) How do the results from (a) and (b) compare?
A. Having an estimate of the population proportion reduces the minimum sample size needed.
B. Having an estimate of the population proportion has no effect on the minimum sample size needed.
C. Having an estimate of the population proportion raises the minimum sample size needed.

Added by Sharon A.

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