SOLUTION: How many arrangements are there in the word PROBABILITY

PROBABILITY

That's an 11-letter word.  If we could tell the 2 B's apart and the
2 I's apart, the answer would be 11! However, since we can't, we must 
divide by the number of ways the 2 B's can be swapped within each 
arrangement which is 2!.  Also we must divide by the number of ways 
the 2 I's can be swapped within each arrangement which is also 2!.

Answer:   


Edwin