Data: 59, 74, 73, 66, 80, 84, 90, 110, 37.2, 50, 101.8, 39, 80,
35, 88, 34, 82, 65, 61, 63, 66, 88, 70, 79, 75
b) Given the data above, calculate the 90% Confidence Interval.
(Again, show your work.)
Which is a bigger range, the 95% or 90% confidence interval?
Why?
b) from given data n = 25
xbar = 70 , s = 20.0
The 90% confidence interval for population mean
xbar - ta/2*(s/√n) < < xbar + ta/2*( s/√n)
For a = 0.10 , d.f = n -1 = 24
ta/2 , n-1 = t0.05,24 = 1.71
70 - 1.71*(20/√25) < < 70 + 1.71*(20/√25)
63.16 < < 76.84
This 90% confidence interval for population mean
Width = 76.84 - 63.16 = 13.68
The width of 95% confidence interval is 16.48
The 95% confidence interval has wide range than 90% confidence interval
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