Asked by James
4 different letters are dropped on the floor and then inserted into four differently addressed envelopes. Find the probability that exactly 2 letters are inserted into the proper envelope.
Answers
Answered by
plumpycat
It doesn't take long to list these cases, using uppercase letters to show correct placement and lowercase letters to show incorrect placement:
ABdc
AdCb
AcbD
dBCa
cBaD
baCD
We see there are 6 ways for this event to happen, or 4c2, out of 4! total possible ways of placing the letters in envelopes.
4c2/4! = ______
ABdc
AdCb
AcbD
dBCa
cBaD
baCD
We see there are 6 ways for this event to happen, or 4c2, out of 4! total possible ways of placing the letters in envelopes.
4c2/4! = ______
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.