The marginal product of labor can reduce the cost of producing the current output level. They do so by employing more labor and using less capital. Normally, it is defined as the change in output that is n turn related to the change in a special factor. You need to hold the other inputs in a production constant as well.
When you have done this, you can then calculate the marginal product of labor as the unit change in labor. All of this works to calculate the precise value, which gives you rough estimates of the cost needed. This helps business align their costs accordingly.
