On Blackboard under the Homework folder, you can find a zip file CPS08.zip which contains a database CPS08.csv for full-time, full-year workers age 25-34, with a high school diploma or B.A. /B.S. as their highest degree. A detailed description is given in the pdf file CPS08_Description. In this exercise, you will investigate the the relationship between a worker's age and average hourly earnings (AHE). (a) Assume the wage of people who are 30 or older and the people who are younger than 30 follow normal distribution and have mean / and /2 respectively. Write down the estimators for u and #2. You can take the number of workers who are 30 or older as N, and the number of worker who are younger than 30 as N2