
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
An elevator in a building starts at the ground floor and can only stop at the 18th, 19th, or 20th floor. Assuming there are 5 passengers in the elevator, and each passenger has an equal probability of $\frac {1}{3}$ to get off at each of these three floors, let $\xi$ represent the number of passengers getting off at the 20th floor. Find $P(\xi=4)$.

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