QCEVault

Statistical inference — Question 233

Original QCE Vault practice · 5 marks

Q233 · Practice questionTechnology-freeSimple familiar5 marks

QUESTION 233 (5 marks)

A sample of 100 independent measurements has mean 20. A 95% mean confidence interval, using x‾±1.96s/n\overline x\pm1.96s/\sqrt n, is (19.216,20.784).
a)
Determine the sample standard deviation s.
[2 marks]
b)
For a new sample of size 400 with the same observed mean and standard deviation, find the interval and explain its width change.
[3 marks]
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