QCEVault

Interval estimates for proportions — Question 315

Original QCE Vault practice · 4 marks

Q315 · Practice questionTechnology-activeSimple familiar4 marks

QUESTION 315 (4 marks)

A pilot survey suggests a population proportion of 0.40.4. A larger survey will use a 95%95\% approximate confidence interval with planned margin of error at most 0.0250.025. Use z=1.96z=1.96 and the pilot value for planning.
a)
Determine the minimum integer sample size.
[3 marks]
b)
Explain why this sample size does not guarantee an actual margin of error at most 0.0250.025.
[1 mark]
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