Based on a sample of the salaries of professors at a major university, you perform a multiple regression relating salary (Y) to years of service (X₁) and gender (X₂), where gender = 0 if female, and 1 if male. The prediction equation is:

Salary-hat = 45,000 + 3000(Years) + 4000(Gender) + 1000(Years*Gender)

Based on these results, the estimated average differences in the salaries of a male professor with three years of service and female professor with three years of service would be:

3000 dollars

7000 dollars

5000 dollars

4000 dollars