GMATPrep Probability Problem

[projase]

Four letters are going to be send to four different addresses.

If the letters are to be put into the 4 enveolpes at random, what is the probability that only 1 letter will be put into the envelope with its correct address?

Alt 1/24; 1/8; 1/4; 1/3; 3/8

[thankont]

Not quite sure here but one ans. could be
4C1*1/4*2/3*1/2
combination applies since we have 4 letters
1/4 for 1st letter to be put in correct place
2/3 for 2nd letter to be put in wrong place
1/2 for 3rd letter to be put in wrong place
so ans is 1/3...