Capital One Assessment Test Advanced Applications 3

Question 1

A Capital One data engineer needs to find customers who have accounts but no transactions in 2025. Which SQL approach is most efficient?

Accepted Answer

LEFT JOIN transactions ON customer_id with WHERE transactions.id IS NULL and year = 2025

Answer

A LEFT JOIN with IS NULL on the right table's key efficiently finds unmatched records without a subquery scan.

Question 2

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?

Accepted Answer

11

Answer

$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.

Question 3

In a Capital One credit scoring model, the Gini coefficient of 0.68 indicates what about the model's discriminatory power?

Accepted Answer

Strong ability to separate defaulters from non-defaulters

Answer

A Gini coefficient of 0.68 (AUC ≈ 0.84) indicates strong discriminatory power in distinguishing defaulters from non-defaulters.

Question 4

An analyst writes this Python code: df.groupby('state')['revenue'].agg(['mean','median','std']). What will this output?

Accepted Answer

A DataFrame with mean, median, and standard deviation of revenue for each state

Answer

The groupby + agg call returns a DataFrame indexed by state with three columns: mean, median, and std of revenue.

Question 5

Capital One's fraud detection model has precision of 0.85 and recall of 0.70. What is the F1 score?

Accepted Answer

0.769

Answer

F1 = 2 × (precision × recall) / (precision + recall) = 2 × (0.85 × 0.70) / (0.85 + 0.70) = 1.19 / 1.55 ≈ 0.769.

Capital One Assessment Test Practice Test

Capital One Assessment Test Practice Test

Capital One Assessment Test Advanced Applications 3