QCEVault

Statistical inference — Question 147

Original QCE Vault practice · 7 marks

Q147 · Practice questionTechnology-activeComplex unfamiliar7 marks

QUESTION 147 (7 marks)

A sample of n=144n=144 measurements has mean 25.625.6 and standard deviation 3.63.6. Use z=2.576z=2.576 for a 99%99\% interval.
a)
Construct the approximate 99%99\% confidence interval for the population mean.
[3 marks]
b)
Find the sample size needed to reduce the margin of error to at most 0.500.50 if ss remains 3.63.6.
[2 marks]
c)
Explain how confidence level and sample size separately affect interval width.
[2 marks]
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