
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]


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Given the relationship between the carbon dioxide concentration $y\%$ after ventilation and the time $t$ (unit: minutes) is given by the formula $y=0.05+\lambda{e^{-\frac{t}{9}}}$, and the initial carbon dioxide concentration in a classroom is 2000 ppm, find the time required for the concentration to reach the national standard of 1000 ppm.

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