A mathematical prodigy wishes to put 2 of his indistinguishable IMO gold medals and 2 of his indistinguishable IPhO gold medals and 2 of his indistinguishable IChO gold medals in one row. How many distinct arrangements are possible?
There are 6! ways to arrange 6 indistinguishable medals. But some are indistinguishable so we have to divide by them. 6!/(2!2!2!)=90
:D
