Question 1059761: A researcher wishes to estimate, with 95% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within 5% of the population proportion.
(a) No preliminary estimate is available. Find the minimum sample size needed.
(b) Find the minimum sample size needed, using a prior study that found that 18% of the respondents said their favorite flavor of ice cream is chocolate.
(c) Compare the results from parts (a) and (b).
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A researcher wishes to estimate, with 95% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within 5% of the population proportion.
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(a) No preliminary estimate is available. Find the minimum sample size needed.
Since ME = z*sqrt(pq/n)
n = [z/E]^2*p*q = [1.96/0.05]^2*(1/2)^2 = 385
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(b) Find the minimum sample size needed, using a prior study that found t]hat 18% of the respondents said their favorite flavor of ice cream is chocolate.
n = [1.96/0.05]^2*0.18*0.82 = 227
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(c) Compare the results from parts (a) and (b).
I'll leave that to you.
Cheers,
Stan H.
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