I'm guessing 200.]]>

For the second pair, the same reasoning applies except that there are now only two pairs of different letters so there is a 1 in 5 probability of them matching.

The third pair has a 1 in 3 chance and if all 3 of these pairs match then the last pair must also match.

The total probability is worked out by multiplying all of these together, so it is 1 in (7x5x3x1) or if you want to be really technical, 1 in 7!!, which works out to be 1 in 105.]]>

if i had eight identical pieces of paper, 2 of which had the letter A written on them, 2 with B, 2 with C

and 2 with D written on them , jumbled up upside down on the table . if i was to randomly arrange them into pairs what would the probability be of ending up with AA BB CC DD ?