What is the Greek symbol that used to represent the population mean? What is the symbol we use to...

What is the Greek symbol that used to represent the population mean? What is the symbol we use to represent the sample mean? What are the Greek/Latin symbols for the population standard deviation and the sample standard deviation? What is the mean and standard deviation of these five numbers: 10, 12, 50, 15, 13? Which number better represents the series of numbers from Question 2, the median or the mean? Why?