Data Scientist, Specialist at Vanguard

4 questions, about 3 minutes. This is a diagnostic, not a certification — it estimates your skill readiness, it does not guarantee you are qualified for or will be hired into this role.

1. What does `df.groupby('region')['sales'].sum()` return?

The total sales across the whole dataframe Total sales summed for each distinct region A count of rows per region An error, because groupby requires two columns

2. A p-value of 0.03 from a hypothesis test at a 0.05 significance threshold suggests:

The null hypothesis is definitely false There is statistically significant evidence against the null hypothesis The result is not usable The sample size was too small

3. Which measure of central tendency is least affected by extreme outliers?

Mean Median Range Standard deviation

4. Which library is most commonly used for tabular data manipulation in Python?

pandas flask requests pytest

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