A data analyst loads a sales DataFrame with columns 'region', 'product', 'units', and 'revenue'. The 'revenue' column contains some NaN values that should be treated as 0, while the 'units' column has negative values that are data-entry errors and should be removed. The analyst needs a clean DataFrame for further analysis. Which sequence of operations achieves this?

df = df.dropna(); df = df[df['units'] > 0]

df['revenue'] = df['revenue'].fillna(0); df = df[df['units'] >= 0]

df = df[df['units'] >= 0]; df['revenue'] = df['revenue'].fillna(df['revenue'].mean())

df['units'] = df['units'].fillna(0); df = df[df['revenue'] >= 0]

What is the primary purpose of the groupby() method in Pandas?

To merge two DataFrames on a common column

To split data into groups based on one or more keys and then apply a function to each group

To reshape data from wide to long format

To sort the DataFrame by a column

Python InstitutePCAD - Certified Associate in Data Analytics with Python

Domain 4Objective 1

Data Analysis with Pandas and NumPy PCAD-31 Practice Questions (Page 2)

Part of the Data Analysis and Modeling domain, which accounts for 18.8% of the PCAD-31 exam. Python Institute does not publish an official question count, but from its 60-minute exam (~25–40 total, ~5–5 in this domain), expect 3–3 from this objective — we provide 26 practice questions to prepare you well beyond it. (estimate)

26questions here

6free pages

12concepts

18.8%of the exam

Questions 6–10

6foundation · easy
Which Pandas locator is used to select rows and columns by label, including using boolean arrays for filtering?
Select an answer first
7foundation · easy
Which Pandas function is used to stack two DataFrames vertically (one on top of the other) when they have the same columns?
Select an answer first
8application · medium
A DataFrame 'df' has 10 rows (index 0-9) and 5 columns (A-E). An analyst needs to extract rows 2 through 5 (inclusive) and columns B through D (inclusive). Which slicing operation is correct?
Select an answer first
9application · medium
A data analyst loads a sales DataFrame with columns 'region', 'product', 'units', and 'revenue'. The 'revenue' column contains some NaN values that should be treated as 0, while the 'units' column has negative values that are data-entry errors and should be removed. The analyst needs a clean DataFrame for further analysis. Which sequence of operations achieves this?
Select an answer first
10foundation · easy
What is the primary purpose of the groupby() method in Pandas?
Select an answer first

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Data Analysis with Pandas and NumPy PCAD-31 Practice Questions (Page 2)

Questions 6–10

Which Pandas locator is used to select rows and columns by label, including using boolean arrays for filtering?

Which Pandas function is used to stack two DataFrames vertically (one on top of the other) when they have the same columns?

A DataFrame 'df' has 10 rows (index 0-9) and 5 columns (A-E). An analyst needs to extract rows 2 through 5 (inclusive) and columns B through D (inclusive). Which slicing operation is correct?

What is the primary purpose of the groupby() method in Pandas?

Keep studying — Data Analysis and Modeling