SOLUTION: You wish to estimate with 90% confidence, the proportion of U.S. adults who made one or more emergency room visits in the past year. How large of a sample will you need if your es
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Question 1141129: You wish to estimate with 90% confidence, the proportion of U.S. adults who made one or more emergency room visits in the past year. How large of a sample will you need if your estimate is to be within 3% of the population proportion? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! Largest number or most conservative estimate assumes proportion is 0.5
the half-interval is z*sqrt(p*(1-p)/n)=0.03, the error.
square both sides and multiply through by n
1.645^2*0.25=0.0009n
n=751.67 or 752 people
