Suppose a Monopsonist Hires Its Second Worker and This Hiring

Suppose a monopsonist hires its second worker and this hiring has a marginal factor cost of $75 per day. If the market wage is now $62.50 per day, what was the first employee earning when she worked alone?

A) $40.
B) $45.
C) $50.
D) $55.
E) $60.