[Solved] "An FBI study of thirty-five serial killers [killers of several people, not all at once] revealed that twenty-nine were attracted to pornography and incorporated it into their sexual activity, which included serial rape and murder." This assertion, taken from an antipornography ad, seems to have been intended to show that pornography is a causal factor of serial rape and murder. Does it show that? Variable Costs: Expenses that vary directly with the amount of production output. Total Costs: Total costs encompass the sum of all expenses incurred in the production of goods or services, including fixed and variable costs. Average Total Costs: The total cost of production divided by the number of units produced, representing the per-unit production cost. Marginal Costs: The charge for generating one more unit of a product or service.