Indiafilings Data Scientist Interview Questions and Answers

Q1. Difference between CNN and MLP
Ans. 
CNN is used for image recognition while MLP is used for general classification tasks.
• CNN uses convolutional layers to extract features from images while MLP uses fully connected layers.

• CNN is better suited for tasks that require spatial understanding like object detection while MLP is better for tabular data.

• CNN has fewer parameters than MLP due to weight sharing in convolutional layers.

• CNN can handle input of varying
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Q1. Work done in previous companty
Ans. 
Developed machine learning models to predict customer churn and optimize marketing campaigns.
• Built predictive models using Python and scikit-learn

• Utilized SQL to extract and manipulate data for analysis

• Collaborated with cross-functional teams to implement data-driven solutions
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Q1. SQL basic questions
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Q2. Python - pandas, numpy based questions
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Q1. What is Gradient Descents?
Ans. 
Gradient descent is an optimization algorithm used to minimize a function by iteratively moving in the direction of steepest descent.
• Gradient descent is used to find the minimum of a function by taking steps proportional to the negative of the gradient at the current point.

• It is commonly used in machine learning to optimize the parameters of a model by minimizing the loss function.

• There are different variants of gradie...read more
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Q2. What is LSTM?, and what are the gates in it?
Ans. 
LSTM (Long Short-Term Memory) is a type of recurrent neural network designed to handle long-term dependencies.
• LSTM has three gates: input gate, forget gate, and output gate.

• Input gate controls the flow of information into the cell state.

• Forget gate decides what information to discard from the cell state.

• Output gate determines the output based on the cell state.
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Q3. They gave me a link to dataset and started saying the operations to apply on that. E.g, value_counts, null_values, fill the values with mean,etc.
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Q4. What is t-test? What is Mean, Median and Mode and where to use these?
Ans. 
T-test is a statistical test used to determine if there is a significant difference between the means of two groups.
• Mean is the average of a set of numbers, median is the middle value when the numbers are ordered, and mode is the most frequently occurring value.

• Mean is sensitive to outliers, median is robust to outliers, and mode is useful for categorical data.

• T-test is used to compare means of two groups, mean is used...read more
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Q5. What is RANDOM FOREST ?
Ans. 
Random Forest is an ensemble learning method used for classification and regression tasks.
• Random Forest is a collection of decision trees that are trained on random subsets of the data.

• Each tree in the forest makes a prediction, and the final prediction is the average (regression) or majority vote (classification) of all trees.

• Random Forest helps reduce overfitting and improve accuracy compared to a single decision tre...read more
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I was asked Python, sql, coding questions

Case study on how would you identify the total number of footfall on a airport

Q1. ML concepts , regression, regularization etc
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Q1. Self Intro and projects discussion
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Q2. Feature selection methods
Ans. 
Feature selection methods help in selecting the most relevant features for building predictive models.
• Feature selection methods aim to reduce the number of input variables to only those that are most relevant.

• Common methods include filter methods, wrapper methods, and embedded methods.

• Examples include Recursive Feature Elimination (RFE), Principal Component Analysis (PCA), and Lasso regression.
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Round duration - 60 Minutes
Round difficulty - Easy

Round duration - 60 Minutes
Round difficulty - Easy

There were 10 MCQs ranging from Aptitude to Programming MCQs to basics of Data Science.
The coding question only the optimized solution was accepted

Q1. 
Special Sum of Array Problem Statement
Given an array 'arr' containing single-digit integers, your task is to calculate the total sum of all its elements. However, the resulting sum must also be a single-...read more
Ans. 
Calculate the total sum of array elements until a single-digit number is obtained by repeatedly summing digits.
• Iterate through the array and calculate the sum of all elements.

• If the sum is a single-digit number, return it. Otherwise, repeat the process of summing digits until a single-digit number is obtained.

• Return the final single-digit sum.
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Round duration - 45 minutes
Round difficulty - Easy

The interview happened in the evening. It was an online video call.
The interviewer was very cooperative. I would say it was rather a discussion session between us.

Q1. 
Clone a Linked List with Random Pointers
Given a linked list where each node contains two pointers: one pointing to the next node and another random pointer that can point to any node within the list (or ...read more
Ans. 
Create a deep copy of a linked list with random pointers.
• Iterate through the original linked list and create a new node for each node in the list.

• Store the mapping of original nodes to new nodes in a hashmap to handle random pointers.

• Update the random pointers of new nodes based on the mapping stored in the hashmap.

• Return the head of the copied linked list.
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Round duration - 10 Minutes
Round difficulty - Easy

It was late night
It was a telephonic call