Granted the weight and the specific gravity of a body, we can calculate its volume. 假设已知一个物体的重量和比重，我们就能算出它的体积。
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。
