There are 9 jars each with unique labels.
Someone has come and removed all the labels and mixed them up.
If you put the labels back on the jars (without knowing the contents), what is the expected number of labels which would match the contents?
(In reply to
just thoughts by not_so_einstein)
chance of the first label being correct = 1/9
chance of second label being correct given first label correct = 1/8
chance of second label correct given first label incorrect and not 2nd label = 1/8
chance of second label correct given first label incorrect and is second label = 0
wow, this will produce a alot of terms!!
sum them up and divide by 8! (which is the same as dividing by 9! and then multiplying by the original 9 jars), as a guess, I would expect the answer to be about 2.5
I'd bet theres a neat mathematical simplification.
brute force
