Could you please show me your calculation ?

A survey company wants to determine the mean income of middle level employees in the retail industry. A random sample of 500 employees reveals a sample mean of $5500. The standard deviation of this population is $2700. The company would like answers to the following questions:

a. What is the population mean? What is a reasonable value to use as an estimate of the population mean?

b. What is a reasonable range of values for the population mean, state any assumptions? (3 marks)

c. What do these results mean?