Petronas Lead Data Scientist Interview Questions and Answers

Contains questions on aptitude, statistics and SQL

Q1. 1. Processes of data analysis 2. Data cleaning process 3. Project discussion on my data analyst project 4. Case study related to the company
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Q1. 1. Behavioral questions 2. On company values
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Q1. Explain your project
Ans. 
Developed a predictive model to forecast sales based on historical data
• Collected and cleaned sales data from multiple sources

• Performed exploratory data analysis to identify trends and patterns

• Built a machine learning model using regression techniques

• Evaluated model performance using metrics like RMSE and MAE
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Q2. Oops concept was asked
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Mostly easy questions

Cheating overview like should we do it as everyone is doing

If everyone is cheating you should also do it?

Q1. Everyhting about project..
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Q2. Linear vs logistic regression
Ans. 
Linear regression is used for continuous variables, while logistic regression is used for binary outcomes.
• Linear regression is used to predict a continuous outcome based on one or more input variables.

• Logistic regression is used to predict the probability of a binary outcome based on one or more input variables.

• Linear regression assumes a linear relationship between the independent and dependent variables, while logist...read more
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Q3. Normalization in dbms
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Normalization in DBMS is the process of organizing data in a database to reduce redundancy and improve data integrity.
• Normalization involves breaking down data into smaller, more manageable tables and establishing relationships between them.

• It helps in reducing data redundancy, minimizing data anomalies, and improving data consistency.

• There are different normal forms such as 1NF, 2NF, 3NF, BCNF, and 4NF, each with spec...read more
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Q4. List array difference etc
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Array difference is finding the elements that are present in one array but not in another.
• Use set operations like difference to find elements in one array but not in another.

• Example: arr1 = ['a', 'b', 'c'], arr2 = ['b', 'c', 'd'], arr_diff = set(arr1) - set(arr2) = ['a']
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Q1. Resume Based questions and ML & DL basics
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Q2. BERT and CNN models
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Q1. LRU Cache Implementation
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2 question :

1. Find the longest common subsequence in 2 strings
2. find the 5th highest revenue from the table in last 28 days in a particular region

I was given a list of book, genre of books and books and rating of books . All list was of equal length n.

There were 2 methods which need to be implemented
1. get highest rating of book by genre . if rating are same then in lexographical order
2. update book rating by book name

Q1. These questions were basic
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Q2. There were lots of imaginative situation given and then I was asked to say what I would do in those situation
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Q1. What is the purpose of using Common Table Expressions (CTE) in SQL?
Ans. 
CTEs are used in SQL to create temporary result sets that can be referenced within a query.
• CTEs improve readability and maintainability of complex queries

• They can be recursively referenced to solve hierarchical problems

• CTEs can be used to simplify queries by breaking them into smaller, more manageable parts
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