Formula using 99% confidence interval:
CI99 = mean ± [(2.58)(sd/√n)]
Note: Within the brackets is the margin of error.
Your data:
mean = 5.15
sd = 1.68
n = 4400
Plug the values into the formula and calculate.
I hope this will help get you started.
The National Center for Education surveyed 4400 college graduates about the lengths of time required to earn their bachelor's degrees. The sample mean is 5.15 years, and assume that standard deviation is known to be 1.68 years. Based on the sample data, construct the 99% confidence interval for the mean time required by all college graduates. Also determine the margin of error, E.
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