PhonePe Decision Scientist Interview Questions and Answers

Round duration - 60 Minutes
Round difficulty - Medium

Interview was in afternoon.
The interviewer was very polite and clearly explained me each and every detail about the questions.

Q1. 
Sum of Squares of First N Natural Numbers Problem Statement
You are tasked with finding the sum of squares of the first N natural numbers for given test cases.
Input:
The first line contains an integer ...read more
Ans. 
The task is to find the sum of squares of the first 'N' natural numbers.
• Iterate from 1 to N and calculate the square of each number

• Add all the squares together to get the final sum

• Return the sum as the result
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Round duration - 30 minutes
Round difficulty - Medium

Interview was in the afternoon. 
Interviewer was very friendly.

Q1. What is the order of execution of SQL clauses?
Ans. 
The order of execution of SQL clauses is: SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY.
• The SELECT clause is executed first to retrieve the desired columns from the table.

• The FROM clause is executed next to specify the table(s) from which the data is retrieved.

• The WHERE clause is executed after the FROM clause to filter the rows based on specified conditions.

• The GROUP BY clause is executed to group the rows based on ...read more
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Q2. How do you find the count of visitors that came today and the count of new visitors that arrived today?
Ans. 
To find the count of visitors and new visitors that came today in a database management system (DBMS).
• Use a query to filter the visitors based on the current date.

• Count the total number of visitors using the COUNT function.

• To find new visitors, compare the current date with the date of their first visit.

• Use the DISTINCT keyword to count only unique new visitors.
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Q3. Find the department-wise highest salary of the employees.
Ans. 
The query finds the highest salary for each department.
• Use the GROUP BY clause to group the employees by department.

• Use the MAX() function to find the highest salary for each department.

• Combine the MAX() function with the GROUP BY clause to get the department wise highest salary.
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Round duration - 90 Minutes
Round difficulty - Medium

Interview held in the evening.
There were two interviewer.
One was asking the technical questions related to sql and python and other related to business case study and Machine learning.

Q1. How can you find the monthly salary of each employee?
Ans. 
To find the salary of each employee per month, you need access to a database management system (DBMS) that stores employee data.
• Access the DBMS and locate the table that stores employee information.

• Identify the column that contains the salary information.

• Retrieve the salary data for each employee and calculate the monthly salary.

• Store the monthly salary information in a suitable data structure, such as an array of stri
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Q2. What are underfitting and overfitting in machine learning models?
Ans. 
Underfitting and overfitting are common problems in machine learning models.
• Underfitting occurs when a model is too simple and fails to capture the underlying patterns in the data.

• Overfitting happens when a model is too complex and learns the noise or random fluctuations in the training data.

• Underfitting leads to high bias and low variance, while overfitting leads to low bias and high variance.

• To address underfitting, ...read more
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Q3. Can you explain the concept of Random Forest?
Ans. 
Random Forest is an ensemble learning method that combines multiple decision trees to make predictions.
• Random Forest is a supervised learning algorithm used for both classification and regression tasks.

• It creates a multitude of decision trees and combines their predictions to make a final prediction.

• Each decision tree is trained on a random subset of the training data and features.

• Random Forest reduces overfitting and ...read more
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