
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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With the rapid development of the "Internet + transportation" model, "shared bicycles" have appeared successively in many cities. In order to understand the satisfaction of users in a certain area with the services provided, a certain operating company randomly surveyed 10 users and obtained satisfaction ratings of 92, 84, 86, 78, 89, 74, 83, 77, 89.  
$(1)$ Calculate the sample mean $\overline{x}$ and variance $s^{2}$;  
$(2)$ Under condition (1), if the user's satisfaction rating is between $({\overline{x}-s,\overline{x}+s})$, then the satisfaction level is "$A$ grade". Estimate the percentage of users in the area whose satisfaction level is "$A$ grade".  
Reference data: $\sqrt{30}≈5.48, \sqrt{33}≈5.74, \sqrt{35}≈5.92$.

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