Announcements for 84 upcoming engineering conferences were randomly picked from a stack of IEEE Spectrum magazines. The mean length of the conferences was 3.94 days, with a standard deviation of 1.28 days. Assume the underlying population is normal. Define in words the random variable X. Which distribution should you use for this problem? Why?

Announcements for 84 upcoming engineering conferences were randomly picked from a stack of IEEE Spectrum magazines. The mean length of the conferences was 3.94 days, with a standard deviation of 1.28 days. Assume the underlying population is normal.
Define in words the random variable X.
Which distribution should you use for this problem? Why?
Construct a 95% confidence interval for the population mean length of engineering conferences.
-state the confidence interval
-sketch the graph
-calculate the error bound