This Question: 8 pts 24 of 31 (19 complete) A researcher wishes to estimate, wit

Question

This Question: 8 pts 24 of 31 (19 complete) A researcher wishes to estimate, with 90% confidence, the population proportion o adults who say chocolae is ther a on e ice cream a or er estimate must be accurate within 3% d the po (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 20% of the respondents said their favorite flavor of ice cream is chocolate (c) Compare the results from parts (a) and (b) aton o on (a) What is the minimum sample size needed assuming that no prior information is available? (Round up to the nearest whole number as needed) (b) What is the minimum sampl e size needed using a pror study that found that 20% of the respondents said their favorite ice cream flavor is chocolate? n =L(Round up to the nearest whole number as needed) (c) How do the results from (a) and (b) compare? A. Having an estimate of the population proportion reduces the minimum sample size needed O B. Having an estimate of the population proportion has no effect on the minimum sample size needed ° C. Having an estimate of the population proportion raises the minimum sample size needed Cick to select your answer(s)

Explanation / Answer

90% confidence means a critical value of 1.645

a)

Since we do not have any estimate of p, we assume p=0.5

n=Za/2^2*p(1-p)/e^2

n=(1.645)^2*0.5*0.5/0.03^2=751.6736=752

b)

n=Za/2^2*p(1-p)/e^2

n=(1.645)^2*0.2*0.8/0.03^2=481.07=482

c)

A. Having an estimate of the population proportion reduces the minimum sample size required

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