100+ Data Analyst Intern Interview Questions and Answers

The Water Jug Problem involves determining if a target measurement can be achieved using two jugs of different capacities and specific operations.

• Start by filling one jug and transferring water between the jugs to reach the target measurement.

• Consider all possible combinations of filling, emptying, and transferring water between the jugs.

• Keep track of the states of both jugs and the amount of water in each jug during the operations.

• If the target measurement is reached, return...read more

Implement insertion sort on a singly linked list to sort the elements in-place.

• Iterate through the linked list and for each node, find its correct position in the sorted part of the list

• Adjust pointers to insert the node in the correct position

• Repeat this process until all nodes are sorted

loc is label-based indexing while iloc is integer-based indexing in data science. Dashboards are visual tools for data analysis.

• loc is used for selecting rows and columns by labels

• iloc is used for selecting rows and columns by integer position

• Dashboards are visual representations of data for easy analysis and decision-making

Different types of keys in a database include primary key, foreign key, unique key, and composite key.

• Primary key: uniquely identifies each record in a table, must be unique and not null.

• Foreign key: establishes a link between two tables, ensures referential integrity.

• Unique key: ensures that all values in a column are unique.

• Composite key: combination of two or more columns to uniquely identify a record.

MTD stands for Month-to-Date. It refers to the period from the beginning of the current month up to the present date.

• MTD is a common term used in financial and business reporting to track performance within a specific month.

• To create MTD, you would sum up the data from the beginning of the month up to the current date.

• For example, if you are calculating MTD sales for January 2022 on January 15th, you would sum up all sales data from January 1st to January 15th.

• MTD is often us...read more

Pick a fruit from the jar labeled Apples and Oranges, then pick a fruit from the jar labeled Oranges (since it can't be Oranges), and finally pick a fruit from the jar labeled Apples (since it can't be Apples).

• Pick a fruit from the jar labeled Apples and Oranges

• Since the jar labeled Oranges can't be Oranges, it must be Apples and Oranges

• The remaining jar must be Apples

Data is information collected and stored for analysis and decision-making purposes in an organization.

• Data is raw facts and figures that need to be processed to provide meaningful information.

• It is crucial for organizations to make informed decisions, identify trends, and improve performance.

• Examples of data in an organization include sales figures, customer demographics, and website traffic.

• Data can be structured (in databases) or unstructured (like text documents or social ...read more

Data modeling is the process of creating a visual representation of data structures and relationships.

• Data modeling involves defining the structure of data, its storage, and how it will be accessed and manipulated.

• Types of data models include conceptual, logical, and physical models.

• Conceptual models focus on high-level business concepts and relationships.

• Logical models define the structure of the data without considering how it will be implemented in a database system.

• Physic...read more

Create a dataset with names and phone numbers, then extract the sum of digits from the phone numbers.

• Use pandas to create a DataFrame for the dataset.

• Define a function to calculate the sum of digits in a phone number.

• Apply the function to the phone number column to create a new column with the sums.

• Example function: def sum_of_digits(phone): return sum(int(digit) for digit in phone if digit.isdigit())

Python code to check if a sentence is palindrome or not

• Remove all spaces and convert to lowercase

• Reverse the string and compare with original

• If both are same, then it is a palindrome

Separate lines in standard output in C++ are used to display different pieces of information on separate lines for better readability.

• Separate lines are used to display different outputs or messages in a clear and organized manner.

• They are commonly used with the 'endl' or ' ' characters to move to the next line.

• For example, cout << 'Hello' << endl; will display 'Hello' on one line and move to the next line for the next output.

I start by defining the problem, collecting relevant data, cleaning and organizing the data, performing analysis using statistical methods and tools, and finally interpreting and presenting the results.

• Define the problem statement and objectives of the analysis

• Collect relevant data from various sources

• Clean and organize the data to ensure accuracy and consistency

• Perform analysis using statistical methods and tools such as Excel, Python, or R

• Interpret the results and present f...read more

Analyze CSV data using Python and export results to an Excel file for further insights.

• Import necessary libraries: Use pandas for data manipulation and openpyxl for Excel file handling.

• Read the CSV file: Use pandas' read_csv() function to load the data into a DataFrame.

• Data cleaning: Handle missing values and outliers using methods like dropna() or fillna().

• Data analysis: Perform operations like groupby(), aggregation, or statistical analysis to derive insights.

• Export to Exce...read more

List of SQL languages and their brief explanation

• SQL (Structured Query Language) is a standard language for managing relational databases

• T-SQL (Transact-SQL) is a proprietary extension of SQL used by Microsoft SQL Server

• PL/SQL (Procedural Language/Structured Query Language) is Oracle Corporation's proprietary extension of SQL

• MySQL is an open-source relational database management system that uses SQL

• PostgreSQL is an open-source object-relational database management system that...read more

I am familiar with various tech stacks including Python, SQL, and JavaScript for data analysis and development tasks.

• Python: Proficient in using libraries like Pandas and NumPy for data manipulation and analysis.

• SQL: Experienced in writing complex queries for data extraction and reporting in databases like MySQL and PostgreSQL.

• JavaScript: Familiar with frameworks like React for building interactive web applications.

• Data Visualization: Skilled in using tools like Tableau and M...read more

A double linked list is a data structure where each node contains a reference to the previous and next node.

• In a linked list, each node contains a reference to the next node only, while in a double linked list, each node contains references to both the previous and next nodes.

• Double linked lists allow for traversal in both directions, making operations like deletion and insertion easier compared to single linked lists.

• Example: In a double linked list, a node might have pointe...read more

Hash map is a data structure that stores key-value pairs and allows fast retrieval of values based on keys.

• Hash map uses hashing to store and retrieve values based on keys

• It allows null values and null keys

• It is not synchronized and not thread-safe

• Example: HashMap<String, Integer> map = new HashMap<>();

• map.put("apple", 1); int value = map.get("apple");

Super key is a set of attributes that uniquely identifies a record, while foreign key is a reference to a primary key in another table.

• Super key is a combination of one or more attributes that uniquely identifies a record in a table.

• Foreign key is a field in a table that refers to the primary key of another table.

• Super key can have additional attributes that are not necessary for uniqueness.

• Foreign key establishes a relationship between two tables.

• Example: In a database of st...read more

4-stroke engines have 4 strokes per cycle, while 2-stroke engines have 2 strokes per cycle.

• 4-stroke engines are more fuel-efficient and produce less pollution than 2-stroke engines.

• 2-stroke engines are simpler and lighter than 4-stroke engines.

• 4-stroke engines have separate intake, compression, power, and exhaust strokes, while 2-stroke engines combine intake and compression, and power and exhaust strokes.

• Examples of 4-stroke engines include those found in cars, while example...read more

Approximately 500 paper cups may be used in a day in an average office.

• Consider the number of employees in the office

• Think about the average number of hot beverage drinkers

• Factor in the number of meetings and events held in the office

• Take into account the availability of reusable cups

• Estimate based on personal experience or observation

The dataset consists of customer purchase history and demographic information. Difficulties faced include data cleaning and missing values.

• Dataset includes customer ID, purchase amount, purchase date, age, gender, and location.

• Difficulties faced include handling missing values in the age and location columns.

• Data cleaning involved removing duplicates and outliers to ensure accurate analysis.

• Normalization and standardization of data for model preparation.

Outliers in a boxplot are defined as data points that fall below Q1 - 1.5*IQR or above Q3 + 1.5*IQR.

• Calculate the interquartile range (IQR) by subtracting Q1 from Q3.

• Identify the lower bound as Q1 - 1.5*IQR and the upper bound as Q3 + 1.5*IQR.

• Any data points below the lower bound or above the upper bound are considered outliers.

• For example, if Q1 = 10, Q3 = 20, and IQR = 5, then the lower bound = 10 - 1.5*5 = 2.5 and the upper bound = 20 + 1.5*5 = 27.5.

Joins are used to combine rows from two or more tables based on a related column between them.

• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN returns rows when there is at least one match in both tables.

• LEFT JOIN returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN returns all rows from the right table and the matched rows from the left table.

• FULL JOIN returns rows when there is a match in one of the tabl...read more

Power BI is a business analytics tool used to visualize and analyze data. Power Query is a data transformation and shaping tool in Power BI.

• Power BI is a powerful business intelligence tool developed by Microsoft.

• It allows users to connect to various data sources, transform and clean the data, and create interactive visualizations and reports.

• Power BI enables data analysts to gain insights and make data-driven decisions.

• Power Query is a data transformation and shaping tool wi...read more

I handle missing data by identifying, analyzing, and applying appropriate techniques to ensure data integrity and usability.

• Identify missing values using methods like .isnull() in pandas.

• Analyze the pattern of missing data to determine if it's random or systematic.

• Use imputation techniques, such as filling missing values with the mean or median.

• Consider dropping rows or columns with excessive missing data if they don't significantly impact analysis.

• For inconsistent data, stan...read more

Memory management and hash map are important concepts in Java programming.

• Memory management is the process of allocating and deallocating memory in a program.

• Java uses automatic memory management through garbage collection.

• Hash map is a data structure that stores key-value pairs and uses hashing to retrieve values efficiently.

• Java's HashMap class implements the Map interface and provides constant-time performance for basic operations.

• It is important to properly manage memory ...read more

SQL joins are used to combine rows from two or more tables based on a related column between them. Window functions perform calculations across a set of table rows that are related to the current row.

• SQL joins are used to retrieve data from multiple tables based on a related column between them (e.g. INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN).

• Window functions are used to perform calculations on a set of rows related to the current row (e.g. ROW_NUMBER(), RANK(), LAG(), LEA...read more