Suppose That a Regional Health Authority Is the Only Employer

Suppose that a regional health authority is the only employer of nurses,and further,suppose that nurses are not unionized.The 625 currently employed nurses are paid $27 per hour.To attract an additional nurse,the employer must increase the wage to $28 per hour.The marginal cost of this additional worker is

A) $27
B) $17 500
C) $28
D) $653
E) $17 528