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smc

counting and probability intermediate

Problem

How many distinguishable rearrangements of the letters in have both the vowels first? (For instance, is one such arrangement, but is not.)
(A)
(B)
(C)
(D)
Solution
We consider the vowels and consonants separately. There are vowels ( and ), giving choices for the first two letters; similarly, there are consonants (, , , and two s), which would give possible choices for letters to , except that since the two s are indistinguishable, this actually counts each order exactly twice. Therefore the number of possible orderings of the consonants is , giving a total of possible rearrangements.
Final answer
B