Mary Is Considering Hiring Another Worker in an Assembly Line

Multiple Choice

Mary is considering hiring another worker in an assembly line for MP3 speakers. Mary knows the average product of labor is 15 speakers per day. She also believes that the next worker hired will produce an extra 12 speakers per day. A speaker sells for $10. Assuming that the market for speakers is perfectly competitive, Mary should hire another worker:

A) only if the new worker's marginal product is 12 or more.
B) only if the new worker's daily wage is $150 or less.
C) only if the new worker's daily wage is $120 or less.
D) since the marginal product is below the average product.