Three letters are dictated to three person and an envelope is addressed to each of them, the letters are inserted into the envelopes at random so that each envelope contains exactly one letter. Find the probability that at least one letter is in its proper envelope.

Explanation

To solve the problem of finding the probability that at least one letter is in its proper envelope, we can follow these steps:

### Step 1: Understand the Total Outcomes
We first need to determine the total number of ways to insert 3 letters into 3 envelopes. Since each letter can go into any of the envelopes, the total number of arrangements (or permutations) is given by:
\[ 3! = 6 \]
This means there are 6 possible ways to distribute the letters into the envelopes.
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