If you convert every potential opportunity into an hourly wage, it makes the trade-off clear. 如果你把每个潜在的机会都换算成小时工资，是否值得花时间省钱就一目了然了。
To do this, we weight the hourly wage for each grade by its proportion of the total labor required to produce the product. 为此，把每一等级的小时工资，以生产这种产品所消耗的该等级劳动量占总劳动量的比重为权数，进引加权。
