
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
A certain factory produces three different types of products, A, B, and C, with the ratio of their quantities being 3:4:7. Now, a stratified sampling method is used to take a sample of size $n$. There are 15 units of product A in the sample. Therefore, the sample size $n$ is _____.

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