Question 1197051

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Hi

Using Excel Function:
=CONFIDENCE(alpha, sd, size)
       (to one decimal point) ME 
=CONFIDENCE.T(.05, 15, 51) = 4.2  95%   CI = 120 - 4.2 < {{{mu}}} < 120 + 4.2
=CONFIDENCE.T(.1, 15, 51) =  3.5  90%   CI = 120 - 3.5 < {{{mu}}} < 120 + 3.5
=CONFIDENCE.T(.2, 15, 51) =  2.7  80%   CI = 120 - 2.7 < {{{mu}}} < 120 + 2.7

Effect on the confidence interval estimate of decreasing the confidence level:
 ME gets smaller ⇒  Interval gets smaller

Using ME ={{{ z*sigma/sqrt(n)}}}
One can see as z gets smaller ⇒  ME gets smaller ⇒ Interval gets smaller

Wish You the Best in your Studies. 
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