问题如下：
Assume that the days-of-sales-outstanding(DSO) of PZ Corporation in 2016 is 18 days. An analyst in PZ Corporation believed that the PZ's days-of-sales-outstanding(DSO) is going to decline to 12 days in 2017. Total revenue in 2016 were $400 million and the expected revenue is going to increase to $450 million in 2017. In order to get a lower DSO, the average receivable balance differed from 2016 to 2017 is most accurate to:
选项：
A. $9.0million.
B. $9.0million.
C. $4.9million.
解释：
C is correct.
Receivable turnover=365/DSO.
In 2016, the receivable turnover=365/18=20.3.
In 2017,the receivable turnover=365/12=30.4.
Average receivable balance=sales/receivable turnover.
In 2016, the average receivable balance=$400,000,000/20.3=$19,704,434.
In 2017, the average receivable balance=$450,000,000/30.4=$14,802,632.
The difference between 2016 and 2017 is $19,704,434-$14,802,632=$4,901,801=$4.9million.
average receivable balance为什么是这么算的
