
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 certain high school's sophomore class (Class 4), there are 28 male students and 21 female students. A stratified sampling method is used to select a survey group from all the students in the class to investigate their awareness of the new traffic regulations implemented starting January 1, 2013. It is known that the probability of a male student being selected is $\frac{1}{7}$. The number of female students selected is ______.

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