Answer:
228 of them are made from wool, but there is no enough information to determine how many would he has in stock.
Explanation:
Mr Ollivander's stuffed bear shop has 456 bears in stock, and exactly half of them are made from wool, this means that 1/2 of 456 are made from wool
1/2 of 456 = 1/2 × 456 = 456/2 = 228.
That is 228 of them are made from wool.
However, nothing tells us that this is all he has in his stock. There is no information available to determine how many would he has in stock.