
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
An enterprise, in response to the implementation of the national policy on reducing sewage discharge, has installed sewage filtration and discharge equipment. In the filtration process, the relationship between the pollutant content $M$ (unit: $mg/L$) and time $t$ (unit: $h$) is given by $W=M_{0}e^{-kt}$ (where $M_{0}$ and $k$ are positive constants). It is known that after 1 hour, the equipment can filter out $50\%$ of the pollutants. Determine the time required to filter out $90\%$ of the pollutants.

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