Advanced Applications Flashcards
7 cards from real Capital One Assessment Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Advanced Applications flashcards as text
A Capital One data engineer needs to find customers who have accounts but no transactions in 2025. Which SQL approach is most efficient?
Answer: LEFT JOIN transactions ON customer_id with WHERE transactions.id IS NULL and year = 2025
A LEFT JOIN with IS NULL on the right table's key efficiently finds unmatched records without a subquery scan.
A portfolio of 500 credit accounts has an average balance of $4,200 with a standard deviation of $800. Assuming normal distribution, approximately how many accounts have balances above $5,800?
Answer: 11
$5,800 is 2 standard deviations above the mean; approximately 2.3% of a normal distribution lies above +2σ, so 0.023 × 500 ≈ 11 accounts.
In a Capital One credit scoring model, the Gini coefficient of 0.68 indicates what about the model's discriminatory power?
Answer: Strong ability to separate defaulters from non-defaulters
A Gini coefficient of 0.68 (AUC ≈ 0.84) indicates strong discriminatory power in distinguishing defaulters from non-defaulters.
An analyst writes this Python code: df.groupby('state')['revenue'].agg(['mean','median','std']). What will this output?
Answer: A DataFrame with mean, median, and standard deviation of revenue for each state
The groupby + agg call returns a DataFrame indexed by state with three columns: mean, median, and std of revenue.
Capital One's fraud detection model has precision of 0.85 and recall of 0.70. What is the F1 score?
Answer: 0.769
F1 = 2 × (precision × recall) / (precision + recall) = 2 × (0.85 × 0.70) / (0.85 + 0.70) = 1.19 / 1.55 ≈ 0.769.
Which approach correctly handles a many-to-many relationship between Capital One customers and credit products in a relational database?
Answer: Create a junction table with foreign keys to both the customers and products tables
A junction (bridge) table with foreign keys to both parent tables is the standard relational approach for many-to-many relationships.
A Capital One analyst needs to calculate the cumulative sum of daily transactions partitioned by account. Which SQL window function achieves this?
Answer: SUM(amount) OVER (PARTITION BY account_id ORDER BY date ROWS UNBOUNDED PRECEDING)
The window function with ROWS UNBOUNDED PRECEDING computes a running total within each account partition ordered by date.
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