Question 308541
Find a confidence interval for u assuming that each sample is from a normal population
a. x-bar=24,s=3,n=7,90percent
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Comment:  I assume you want t-intervals since you are estimating u.
Since sample size = 7, the degrees of freedom are 6.
Using a TI calculator I found invT(0.95,6) = 1.9432
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Find the standard error = E = 1.9432*s/sqrt(7) = 2.2034
90% CI: 24-2.2034 < u < 24+2.2034
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Use the same procedure on "b", and "c".
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Cheers,
Stan H.
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b. x-bar=42,s=6,n=18,99percent
c. x-bar=119,s=14,n=28,95percent