
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system

In a department store, they received 10 suitcases and 10 keys separately in an envelope. Each key opens only one suitcase, and every suitcase can be matched with a corresponding key.

A worker in the department store, who received the suitcases, sighed:

- So much hassle with matching keys! I know how stubborn inanimate objects can be!! You start matching the key to the first suitcase, and it always turns out that only the tenth key fits. You'll try the keys ten times because of one suitcase, and because of ten - a whole hundred times!

Let’s summarize the essence briefly. A salesperson said that the number of attempts is no more than \(10+9+8+\ldots+2+1=55\), and another employee proposed to reduce the number of attempts since if the key does not fit 9 suitcases, it will definitely fit the tenth one. Thus, the number of attempts is no more than \(9+8+\ldots+1=45\). Moreover, they stated that this will only occur in the most unfortunate scenario - when each time the key matches the last suitcase. It should be expected that in reality the number of attempts will be roughly

\[\frac{1}{2} \times \text{the maximum possible number of attempts} = 22.5.\]

Igor Fedorovich Akulich from Minsk wondered why the expected number of attempts is half the number 45. After all, the last attempt is not needed only if the key does not fit any suitcase except the last one, but in all other cases, the last successful attempt also takes place. Akulich assumed that the statement about 22.5 attempts is unfounded, and in reality, it is a bit different.

**Problem:** Find the expected value of the number of attempts (all attempts to open the suitcases are counted - unsuccessful and successful, in the case where there is no clarity).

Present the answer in LaTex format: \boxed{Your answer}
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