
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 investigate the PM2.5 values in a city, 48 cities are divided into three groups: Group A, B, and C, with the number of cities in each group being 10, 18, and 20, respectively. If stratified sampling is used to select 16 cities, the number of cities that need to be sampled from Group B is ______.

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