SOLUTION: a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x bar = 120 and s = 15. Estimate the population mean with 95% confidence. b

Algebra ->  Statistics  -> Confidence-intervals -> SOLUTION: a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x bar = 120 and s = 15. Estimate the population mean with 95% confidence. b      Log On


   

Question 1197051: a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x bar = 120 and s = 15. Estimate the population mean with 95% confidence.
b. Repeat part (a) with a 90% confidence level.
c. Repeat part (a) with an 80% confidence level.
d. What is the effect on the confidence interval estimate of decreasing the confidence level?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


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%2Asigma%2Fsqrt%28n%29
One can see as z gets smaller ⇒  ME gets smaller ⇒ Interval gets smaller

Wish You the Best in your Studies.