SOLUTION: Suppose the prime minister wants an estimate of the proportion of the population who support his current policy on health care. The prime minister wants the estimate to be within 0

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Question 1118456: Suppose the prime minister wants an estimate of the proportion of the population who support his current policy on health care. The prime minister wants the estimate to be within 0.06 of the true proportion. Assume a 80% level of confidence. The prime minister's political advisors estimated the proportion supporting the current policy to be 0.33. (Round the intermediate calculation to 2 decimal places. Round the final answer to the nearest whole number.)
c. How large of a sample is required?

d. How large of a sample would be necessary if no estimate were available for the proportion that support current policy?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
80% CI is +/-1.28sqrt(p*(1-p)/n)
half-interval is +/-0.06
0.06=1.28sqrt(p*(1-p)/n)
0.0036=1.64*p(1-p)/n, squaring both sides
0.0036n=1.64*0.33*0.67
n=0.36/0.0036
n=100
Use 0.5 for p, if no estimate there.
0.0036=1.64*0.25/n, after squaring
0.0036n=0.41
n=113.88 or 114.