Question 1043432: A researcher wishes to estimate, with 90% confidence, the population proportion of adults who are confident with their country's banking system. His estimate must be accurate within 3% 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 24% of the respondents said they are confident with their country's banking system.
(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 90% confidence, the population proportion of adults who are confident with their country's banking system. His estimate must be accurate within 3% of the population proportion.
(a) No preliminary estimate is available. Find the minimum sample size needed.
n = [1.645/0.03]^2*0.5^2 = 752 when rounded up
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(b) Find the minimum sample size needed, using a prior study that found that 24% of the respondents said they are confident with their country's banking system.
n = [1.645/0.03]^2*0.24*0.76 = 549 when rounded up
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(c) Compare the results from parts (a) and (b).
With (b) you have more information to use to get
the estimate so your sample can be smaller.
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Cheers,
Stan H.
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