Question 1088177: In a poll of 556 human resource professionals, 40.3 % said that body piercings and tattoos were big grooming red flags. Complete parts (a) through (d) below.
a) Among the 556 human resource professionals who were surveyed, how many of them said that body piercings and tattoos were big grooming red flags?
b) Construct a 99% confidence interval estimate of the proportion of all human resource professionals believing that body piercings and tattoos are big grooming red flags.
c) Repeat part (b) using a confidence level of 80% and rounding to three decimal places.
d)Compare the confidence intervals from parts (b) and (c) and identify the interval that is wider. Why is it wider?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! a. It is 556*0.403=224.068 or 224.
b. 99%CI is 0.403+/-2.576(sqrt p*(1-p)/n); sqrt .403*.597/556=0.0208
Therefore, interval is 0.403 +/-0.0536 after multiplying by 2.576
The interval is (0.349, 0.457)
For 80%, use 1.28 for the z-value and get (0.376, 0.430)
the first interval is wider, because to have more confidence, one requires a larger interval in order to obtain it.
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