Graded Quiz: Exploratory Data Analysis :Data Analysis with Python (IBM Data Analyst Professional Certificate) Answers 2025
1. Question 1
Elina wants summary statistics (count, mean, std). What should she use?
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❌ head()
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❌ tail()
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✅ describe()
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❌ summary()
Explanation:
df.describe() gives summary statistics for numerical columns.
2. Question 2
Pearson correlation close to zero means:
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❌ Mean of data near zero
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❌ Uncertainty between variables
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❌ Minimal deviation
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✅ Two variables are not correlated
Explanation:
Correlation ≈ 0 → no linear relationship.
3. Question 3
Reshape data so one variable becomes rows and another becomes columns:
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❌ merge()
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❌ groupby()
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✅ pivot()
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❌ pcolor()
Explanation:
pivot() reshapes long data → wide format with rows vs columns.
4. Question 4
Result of:
df_grp = df_test.groupby(['body-style'], as_index=False).mean()
df_grp['price']
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❌ Averages body-style variable
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❌ Writes mean value of each body-style price to the dataframe (wording unclear)
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❌ Averages price for all body labels
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✅ It averages the price for each body style.
Explanation:
Groupby + mean computes mean price for each body-style category.
5. Question 5
No clear trend between peak RPM and price means:
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✅ Weak or no correlation
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❌ Strong negative
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❌ Uncertain
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❌ Strong positive
Explanation:
Scattered values without trend → very low correlation.
🧾 Summary Table
| Q | Correct Answer | Key Concept |
|---|---|---|
| 1 | describe() | Summary statistics |
| 2 | Variables not correlated | Pearson ≈ 0 |
| 3 | pivot() | Data reshaping |
| 4 | Mean price per body-style | groupby + mean |
| 5 | Weak/no correlation | Relationship analysis |