QCEVault

Interval estimates for proportions — Question 318

Original QCE Vault practice · 4 marks

Q318 · Practice questionTechnology-activeComplex familiar4 marks

QUESTION 318 (4 marks)

Two survey plans use the same assumed population proportion. Plan A uses 400400 responses and a 95%95\% confidence level. Plan B uses a 99%99\% confidence level and aims for a planned margin of error no larger than that of Plan A. Use z95=1.96z_{95}=1.96 and z99=2.576z_{99}=2.576.
a)
Determine the minimum sample size for Plan B.
[3 marks]
b)
Explain why Plan B needs more responses.
[1 mark]
Question linkSyllabus coverage

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