10+ American Express Data Analyst Interview Questions and Answers

The problem involves finding the maximum element in each sliding window of size 'K' in an array of integers.

• Iterate through the array and maintain a deque to store the indices of elements in the current window.

• Remove indices from the deque that are outside the current window.

• Keep the deque in decreasing order of element values to easily find the maximum element in each window.

Explaining a complex joins problem in DBMS

• Discussing the use of different types of joins like inner join, outer join, self join, etc.

• Explaining how to handle null values and duplicates during joins

• Demonstrating a scenario where multiple tables need to be joined based on different keys

A case study on the number of green T-shirts sold in the US.

• Identify the target audience for green T-shirts

• Analyze the market demand for green T-shirts

• Study the sales data of green T-shirts in the US

• Identify the popular brands and styles of green T-shirts

• Analyze the impact of seasonality on sales

• Consider the pricing strategy of green T-shirts

• Identify potential marketing opportunities to increase sales

To determine if a person can be a customer of a private jet company, factors such as income level, travel frequency, and location must be considered.

• Consider the individual's income level to determine if they can afford private jet services

• Evaluate the person's travel frequency to see if they would benefit from the convenience of private jet travel

• Take into account the person's location and travel destinations to assess the need for private jet services

SQL query using CASE WHEN THEN statement

• Use CASE WHEN statement to create conditional logic in SQL queries

• Syntax: SELECT column_name, CASE WHEN condition1 THEN result1 WHEN condition2 THEN result2 ELSE result3 END AS new_column_name FROM table_name

• Example: SELECT name, CASE WHEN age < 18 THEN 'Minor' ELSE 'Adult' END AS age_group FROM customers

Factors such as foot traffic, proximity to banks, crime rates, and demographics should be considered for ATM placements in a city.

• Foot traffic in the area

• Proximity to banks or financial institutions

• Crime rates in the neighborhood

• Demographics of the area (income levels, age groups)

• Accessibility and visibility of the location

• Local regulations and zoning laws

• Availability of power and network connections

• Competition from other ATMs or financial services

• Potential for growth and dev...read more

A p-value is a measure used in statistical hypothesis testing to determine the strength of evidence against the null hypothesis.

• A p-value is the probability of obtaining results as extreme as the observed results, assuming the null hypothesis is true.

• A p-value is compared to a significance level (usually 0.05) to determine if the null hypothesis should be rejected.

• A p-value less than the significance level indicates strong evidence against the null hypothesis.

append() adds elements to a single DataFrame, while concat() combines multiple DataFrames.

• append() is a method used to add rows to a DataFrame.

• concat() is a function used to combine multiple DataFrames along a particular axis.

• append() modifies the original DataFrame, while concat() returns a new DataFrame.

• Example: df1.append(df2) vs pd.concat([df1, df2])

The output of a**2 is the square of the value of a.

• The output is the value of a multiplied by itself

• For example, if a = 3, then the output would be 9 (3*3)