问题如下：
XYZ company calculates inventory at the end of the year by a periodic inventory system. Beginning inventory was 50 units at $1 per unit.
- Quater 1: buy 100 units at $2 per unit
- Quarter 2: buy 200 units at $3 per unit
- Quarter 3: buy 150 unit at $3.5 per unit
- Quarter 4: buy 80 unit at $4 per unit
Total sales for the year were 520 units, compute ending inventory under FIFO and LIFO .
选项：
FIFO
LIFO
$240
$70
$70
$240
$320
$50
解释：
FIFO: ending inventory =60*4=240
LIFO: ending inventory=50*1+10*2=70
FIFO是先进先出，那60个商品不是按照期初50*1+10*2=70吗？
