SOLUTION: a researcher wishes to estimate, with 95% confidence, the porportion of adults who have high-speed internet access. Her estimate mush be accurate within 3% of the true proportion.

Question 989364: a researcher wishes to estimate, with 95% confidence, the porportion of adults who have high-speed internet access. Her estimate mush be accurate within 3% of the true proportion.
(a)find the minimum sample size needed, using a prior study that found that 32% of the respondents said they have high-speed internet access.
(b)find the minimum sample size needed assuming that no preliminary estimate is available
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The z-value for 95% confidence is +/-1.96
z*sqrt{ p*(1-p)/n} =0.03
square both sides and multiply both by n,
z^2*p/(1-p)=0.0009n
3.8416*0.32*0.68=0.0009n
n=929 rounded up.
No preliminary estimate, and one uses 0.5 as the maximum sample size.
3.846*0.5*0.5=0.0009n
n=1068 rounded up.
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