I looked at the question and the answer was directed towards fixed assets - not inventory? They give you the hisotric rates for when specific fixed assets were purchased.
Thanks all - the below confirms the correct logic:
From CFAI, pg 242:
The historical exchange rates used to translate inventory (and cost of goods sold) under the temporal method will differ depending on the cost flow assumption—first in, first out (FIFO); last in, first out (LIFO); or average cost—used to account for inventory. Ending inventory reported on the balance sheet is translated at the exchange rate that existed when the inventory’s acquisition is assumed to have occurred (ie historical).
If FIFO is used, ending inventory is assumed to be composed of the most recently acquired items and thus inventory will be translated at relatively recent exchange rates.
If LIFO is used, ending inventory is assumed to consist of older items and thus inventory will be translated at older exchange rates.
The weighted-average exchange rate for the year is used when inventory is carried at weighted-average cost.
Similarly, cost of goods sold is translated using the exchange rates that existed when the inventory items assumed to have been sold during the year (using FIFO or LIFO) were acquired. If weighted- average cost is used to account for inventory, cost of goods sold will be translated at the weighted-average exchange rate for the year.