Aresearcher wishes to be 95% confident that her estimate of the true proportion of individuals who travel overseas is within 3% of the true proportion. a) find the sample necessary if, in a prior study, a sample of 200 people showed that 40 traveled overseas last year. b) if no estimate of the sample proportion is available, how large should the sample be?

 a) 683   b) 1067

Step-by-step explanation:

The confidence interval for population proportion is given by :-

a) Given : Significance level :

Critical value :

Margin of error :

Formula to calculate the sample size needed for interval estimate of population proportion :-

Hence, the required sample size would be 683 .

b) If no estimate of the sample proportion is available then the formula to calculate sample size will be :-

Hence, the required sample size would be 1067 .

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step-by-step explanation:

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