Latest Questions 209 total
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166How to prepare for a data science interview in 30 days?
**Week 1 — Statistics & Probability**
- Probability distributions, Bayes theorem
- Hypothesis testing, p-values
- A/B testing basics
**We...
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167Most common system design interview questions for software engineers
Top system design questions asked at product companies:
1. **Design a URL shortener** (Bit.ly)
2. **Design Twitter/Instagram** (social medi...
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168What is the difference between useState and useEffect in React?
**useState** — manages state (data that can change over time)
**useEffect** — handles side effects (API calls, subscriptions, timers)
`...
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169What is async/await in JavaScript?
**async/await** is syntactic sugar over Promises that makes asynchronous code look synchronous.
```javascript
// With Promises
fetch('/api/...
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170What is the difference between var, let, and const in JavaScript?
All three declare variables, but with different scope and mutability:
**var:** function-scoped, hoisted, can be redeclared
**let:** block-s...
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171How do you find duplicate rows in SQL?
```sql
-- Find duplicates by email
SELECT email, COUNT(*) as count
FROM users
GROUP BY email
HAVING COUNT(*) > 1;
-- Delete duplicates, kee...
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172What is the difference between WHERE and HAVING in SQL?
**WHERE** filters rows BEFORE grouping
**HAVING** filters groups AFTER GROUP BY
```sql
-- WHERE: filter individual rows
SELECT * FROM emplo...
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173What is the difference between INNER JOIN and LEFT JOIN in SQL?
**INNER JOIN** — returns only rows where there is a match in BOTH tables
**LEFT JOIN** — returns ALL rows from the left table + matching...
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174Top 10 Python interview questions for data science jobs
Here are the most commonly asked Python questions in data science interviews:
1. Difference between list, tuple, and set
2. Explain generat...
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175Is Python enough to get a data science job?
Python alone is NOT enough, but it's the most important skill.
You need:
1. **Python** (Pandas, NumPy, Scikit-learn, Matplotlib)
2. **SQL**...
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176How many months does it take to learn full stack development?
Timeline to become job-ready in full stack:
**With dedicated learning (6-8 hours/day):**
- HTML/CSS/JS basics: 1 month
- React (frontend): ...
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177What is the average salary for a data science fresher in India 2025?
For freshers in India (2025 data):
- **Entry level (0-1 year):** ₹3.5 – ₹7 LPA
- **Junior Data Scientist (1-3 years):** ₹6 – ₹1...
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178How to get a data science job with no experience?
Getting your first data science job without experience is challenging but very doable. Here's a proven roadmap:
1. **Build skills** — Pyt...
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179What is Docker and why do developers use it?
Docker is a containerisation platform that packages your application and all its dependencies into a portable container.
**Why use it:**
- ...
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180What is the difference between AWS EC2 and Lambda?
**EC2 (Elastic Compute Cloud):** Virtual servers you manage
- You control OS, software, scaling
- Always running → pay for uptime
- Best f...
