Question

there are 7 letters and 7 envelopes . find the probability that no letter reaches its correct address???

Answer 1

Hint: probability that no letter reaches the correct address = probability that all letters reach the wrong addresses.

Answer 2

is it related to derangement ????

Answer 3

Letter 1 has 6 ways it could go to a wrong place.
Letter 2 has 5 ways because one letter has already been delivered.
Letter 3 has 4.
Letter 4 has 3.

... and so on

Answer 4

Yes....Permutation and combination..u have to use this

Answer 5

@ParthKohli then it will be like
is it right ???

Answer 6

no....))