Why do we often create a confidence interval for a population mean? Select one:
a. We estimate the population mean with the sample standard deviation. The distribution of the sample standard deviation can often be well approximated by a normal distribution.
b. The mean is the ideal summary of a distribution. Given a population mean you don't really need anything else.
c. We estimate the population mean with the sample mean. The distribution of the sample mean can often be well approximated by a normal distribution.
d. We estimate the population mean with the sample mean. The mean is something most people understand.