NO.PZ2017100901000007
问题如下：
The production relationship between the number of machine hours and total product for a company is presented below.
Diminishing marginal returns first occur beyond machine hour:
选项：
A.3.
B.4.
C.5.
解释：
A is correct.
Diminishing marginal returns occur when the marginal product of a resource decreases as additional units of that input are employed. Marginal product, which is the additional output resulting from using one more unit of input, is presented below.
The marginal product of the third machine hour is 6 and declines thereafter. Consequently, diminishing marginal returns are first evident beyond three machine hours.
考点：边际效用递减
我们首先计算不同产量下的边际产量，如下表所示。
可以看到产量由3增加到4的时候，边际产量由6下降到5，所以产量3的边际效用开始出现递减。
问题①Diminishing marginal returns first occur beyond machine hour:这个问题问的不是MR递减首次出现在什么时候。那不是应该求MR吗
②如果按照答案理解，求MP的拐点，答案是什么意思？每个MP咋求出来的？MP不是边际产量的意思吗？
