问一道题：NO.PZ2016021705000062 [ CFA I ]

47.9 ys. 78.5 ys. is correct. Number of ys of inventory = $2,300/($20,000/365) = 41.975 ys（大家注意此处答案用的是enng数据，但应该使用average inventory) Number of ys of receivables = $2,500/($25,000/365) = 36.5 ys Operating cycle = 41.975 + 36.5 ys = 78.475 ys Note: The net operating cycle is 47.9 ys. Purchases = $20,000 + $2,300 − $2,000 = $20,300 Number of ys of payables = $1,700/($20,300/365) = 30.567 ys The net operating cycle is 78.475 − 30.567 = 47.908 ys 有两个问题没弄懂，1.能不能从概念上帮我区分下cret sales和accounts receivables   2.题目求的是operating cycle，不是net operating cycle，为什么还要减ys of payable？

    李老师上课的时候讲了，如果是给了beginning和enng的inventory，应该是用average的去计算，当时也提到了原版书的课后题的计算方法直接使用enng的数据是不对的。不应该用average inventory计算么。。。

    老师，算出来是47.9啊，应该选b，为什么选c啊？难道还有什么陷阱嘛？

老师，请问算inventory的turnover不是公式分母应该average的inventory么？为什么答案里面直接用了closing inventory呢？