
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
To understand the situation of mass sports activities in factories of a certain city, it is planned to use stratified sampling to select 7 factories for investigation from three districts: A, B, and C. It is known that there are 18, 27, and 18 factories in districts A, B, and C, respectively.

(1) Calculate the number of factories that should be selected from districts A, B, and C, respectively;

(2) If 2 of the 7 selected factories are randomly chosen for a comparative investigation, calculate the probability that at least one of these 2 factories comes from district A using the enumeration method.

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