After analyzing the age-earnings profile for 1,744 workers, it becomes clear to you that the relationship cannot be approximately linear. You estimate the following polynomial regression model, controlling for the effect of gender by using a binary variable that takes on the value of one for females and is zero otherwise:

Earn_hat = -795.90 + 82.93 Age- 1.69 Age2+ 0.015 Age3- 0.0005 Age4- 163.19Female,R2= 0.225,SER=259.78

(283.11) (29.29)(1.06)(0.016)(0.0009)(12.45)

question : 1. Please Test for the significance of theAge4Make sure you show all the steps and graph.

2.What is the effect of changing age from 30 to 31 on earnings, holding constant the gender variable. Explain all your steps.