In: Statistics and Probability
9. (19) A random sample of 64 UPW college students shows that the sample mean GPA is 2.82 with a standard deviation of 0.45.
(a) Construct a 90% Confidence Interval for the mean GPA of all UPW students.
(b) If we want to be 95% confident, and we want to control the maximum error of estimation to 0.1, how many more students should be added into the given sample?
(c) Would you conclude that the mean GPA in UPW is lower than 3 at 5% level of significance?