Stan has an employee, Barbara, who is the only female security guard at the company. Barbara is a "night owl" and loves to work the midnight to 8 a. m. shift for the company. Stan knows that working through the night is potentially more dangerous than working during the day, so he pays her an additional $2 per hour. This wage differential is likely an example of: how many Fulton ounce portions can be obtained from 14 lb of trimmed meat