SOLUTION: An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. In an earlier study, the population proportion was estimated to be

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Question 1141613: An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. In an earlier study, the population proportion was estimated to be 0.33.
How large a sample would be required in order to estimate the fraction of new car buyers who prefer foreign cars at the 95% confidence level with an error of at most 0.02? Round your answer up to the next integer.

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
the half-interval is z(0.975)sqrt (p*(1-p)/n)
0.02=1.96*sqrt(0.33*0.67/n)
square both sides and move n over
0.0004n=3.84*0.33*0.67
n=2122.56
round up to 2123