Confidence Intervals 1. b) d) A random sample of 50 CSCC students has a mean GPA of 2.57. It is known that the population standard deviation for the GPA of all CSCC students is 1.5. Use this information to complete the following: Does the information above provide an estimate of a population mean or a population proportion? Provide a point estimate for the population mean GPA of all CSCC students. Construct and interpret a 90% condence interval for the parameter you selected in part (a)- What is the margin of error of this interval estimate? How large of a sample would you need if you wanted your 95% condence interval to be within 0.4 units of the population parameter