A researcher wishes to be 95% confident that her estimate of the true proportion of individuals who travel overseas is within 4% of the true proportion. Find the sample necessary if, in a prior study, a sample of 200 people showed that 40 traveled overseas last year. If no estimate of the sample proportion is available, how large should the sample be

If in a prior study, a sample of 200 people showed that 40 traveled overseas last year, then n= 385

If no estimate of the sample proportion is available , then n= 601

Step-by-step explanation:

Let p be the prior population proportion of people who traveled overseas last year.

If p is known, then required sample size =

z-value for 95% confidence = 1.96

E = 0.04  (given)

Required sample size = 385

If p is unknown, then required sample size =

, where E = Margin of error , z* =critical z-value.

z-value for 95% confidence = 1.96

E = 0.04  (given)

So,

Required  sample size = 601.

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step-by-step explanation:

find the angular size of the equatorial radius of the earth, if the horizontal parallax of the sun