During the first hour she can hammer 120 nails, the second hour 100 nails, the third hour 90 nails, the fourth hour 60 nails, and the fifth hour 10 nails. Her marginal product in the third hour is nails

90 nails

Explanation:

During the first hour she can hammer 120 nails, the second hour 100 nails, the third hour 90 nails, the fourth hour 60 nails, and the fifth hour 10 nails. Her marginal product in the third hour is 90 nails . Marginal products is the number of extra output or nails hammered by adding another unit of labor (1 more hour). In the third hour, 90 nails were hammered, the marginal output in that additional hour is thus 90.

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