QCEVault

Statistical inference — Question 104

Original QCE Vault practice · 6 marks

Q104 · Practice questionComplex familiar6 marks

QUESTION 104 (6 marks)

A machine-filling process is studied using a sample of 144 packets. The sample has xˉ=502 g\bar x=502\ \mathrm g and s=12 gs=12\ \mathrm g.
a)
Using z=2.576z=2.576, determine an approximate 99% confidence interval for the population mean.
[3 marks]
b)
Assuming s≈12 gs\approx12\ \mathrm g, determine the smallest sample size required so that a 99% confidence interval has total width at most 2 g2\ \mathrm g.
[3 marks]
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