Problema Solution

If 10 letters are to be placed in 10 addresed envolops then what is the probablity that at least one letter is placed in wrong addressed envolop

Answer provided by our tutors

The total number of ways in which 10 latters are placed in 10 envelopes is permutations: 10!

The number of ways in which all letters are placed in the correct envelope is 1.

For atleast 1 letter to be placed in the wrong envelope, we want the compliment of this set.

Hence, 10!−1

Hence, the probability is

(10!-1)/10! = 1 - 1/10! = 0.999999724

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