How to Crack AI/ML Interviews in 2025: Complete Preparation Guide (FAANG to Startups)

December 202518 min read

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The Interview That Changed Everything

Meet Raj, a 27-year-old software engineer earning ₹8 LPA.

  • October 2024: Started learning AI/ML
  • April 2025: Applied to 50 companies
  • May 2025: Got 3 offers:
    • • Amazon: ₹45 LPA
    • • Early-stage startup: ₹28 LPA + equity
    • • Indian unicorn: ₹38 LPA

He chose Amazon.

His monthly salary went from ₹66,000 to ₹3,75,000.

The difference? He didn't just learn AI/ML. He learned how to interview.

This guide reveals exactly what companies ask, how to prepare, and how to negotiate like Raj did.

Before You Start: Master the Fundamentals

Make sure you have the core skills companies are looking for. Read our comprehensive guides:

Understanding the AI/ML Interview Process

Standard Interview Flow (Most Companies)

Round 1: Phone Screen (30-45 min)

  • • Basic ML concepts
  • • Python coding
  • • Past projects discussion

Round 2: Technical Round 1 (60-90 min)

  • • ML algorithms deep dive
  • • Coding (LeetCode medium)
  • • Model evaluation

Round 3: Technical Round 2 (60-90 min)

  • • System design for ML
  • • Project deep dive
  • • Advanced concepts

Round 4: ML Case Study (60 min)

  • • Real business problem
  • • Design ML solution
  • • Trade-offs discussion

Round 5: Behavioral (30-45 min)

  • • Leadership principles
  • • Past experiences
  • • Culture fit

Round 6: Hiring Manager (30 min)

  • • Team fit
  • • Salary discussion
  • • Career goals

Interview Duration Timeline

From application to offer:

  • Startups: 2-4 weeks
  • Unicorns: 4-6 weeks
  • FAANG: 6-10 weeks

The 4 Types of AI/ML Interview Questions

Type 1: ML Theory & Concepts (40% weightage)

What they test: Deep understanding of algorithms

Q1: Explain how gradient descent works. Why might it fail to converge?

Strong Answer:

"Gradient descent iteratively updates parameters by moving in the direction of steepest descent (negative gradient) of the loss function.

θ_new = θ_old - α * ∇L

It might fail to converge due to:

  • Learning rate too high - Overshoots minimum, bounces around
  • Learning rate too low - Takes forever, gets stuck in plateaus
  • Local minima - Gets trapped (less issue with neural networks)
  • Saddle points - Gradient is zero but not a minimum
  • Vanishing gradients - In deep networks, gradients become too small

Solutions: Adaptive learning rates (Adam), momentum, batch normalization, proper initialization."

Q2: Explain bias-variance tradeoff. How do you detect high bias vs high variance?

Strong Answer:

"Bias: Error from wrong assumptions (underfitting)
Variance: Error from sensitivity to training data (overfitting)

Detection:

  • High bias: Low training accuracy, low test accuracy (both bad)
  • High variance: High training accuracy, low test accuracy (huge gap)

Solutions:
High bias: More complex model, more features, less regularization
High variance: More data, regularization (L1/L2, dropout), simpler model
Sweet spot: Balanced error on both training and test sets."

Type 2: Coding (30% weightage)

What they test: Python proficiency + algorithmic thinking

# Pattern 1: Data Manipulation

import pandas as pd
import numpy as np

def clean_data(df):
    # Identify columns to drop (>30% missing)
    threshold = len(df) * 0.3
    cols_to_drop = [col for col in df.columns
                    if df[col].isna().sum() > threshold]
    df = df.drop(columns=cols_to_drop)
    
    # Fill numerical columns
    numerical_cols = df.select_dtypes(include=[np.number]).columns
    for col in numerical_cols:
        if df[col].isna().any():
            df[col].fillna(df[col].median(), inplace=True)
    
    # Fill categorical columns
    categorical_cols = df.select_dtypes(include=['object']).columns
    for col in categorical_cols:
        if df[col].isna().any():
            df[col].fillna(df[col].mode()[0], inplace=True)
    
    return df

LeetCode Problems for AI/ML:

  • • Two Sum, Three Sum (arrays)
  • • Valid Parentheses (stacks)
  • • Binary Tree traversals (trees)
  • • Dynamic Programming basics
  • • Sliding Window problems

Practice: 150 LeetCode problems (Easy: 50, Medium: 90, Hard: 10)

Type 3: System Design for ML (20% weightage)

What they test: Production thinking + scalability

Q1: Design a YouTube recommendation system

Strong Answer Structure:

1. Clarify Requirements

  • • Scale: 2 billion users, 500 hours video/minute uploaded
  • • Latency: <200ms for recommendations
  • • Personalization: Yes, based on watch history
  • • Cold start: Handle new users/videos

2. High-Level Architecture

[User] → [API Gateway] → [Recommendation Service]
                               ↓
                     [Feature Store]
                               ↓
         [Candidate Generation] → [Ranking Model] → [Re-ranking]

3. Model Design

  • Stage 1: Candidate Generation - Two-tower model, ANN for fast retrieval, generate top 1000
  • Stage 2: Ranking - Deep neural network, predict P(watch | user, video, context), rank top 100
  • Stage 3: Re-ranking - Diversity filter, freshness boost, quality filter, final top 20

Type 4: ML Case Studies (10% weightage)

What they test: Business thinking + ML application

Q: Our e-commerce app has 30% cart abandonment. Design an ML solution.

1. Problem Framing

Goal: Reduce abandonment from 30% to 20%

2. ML Approach

Model: Binary classification (will_checkout?)

Model Choice: Gradient Boosting (XGBoost)

3. Intervention Design

  • • High Risk (P < 0.3): Send push notification with 10% off
  • • Medium Risk (0.3-0.7): Browser notification
  • • Low Risk (P > 0.7): No intervention

Company-Specific Interview Patterns

FAANG (Google, Amazon, Meta, Apple, Netflix)

Focus Areas:

  • • System design (40%)
  • • Coding (30%)
  • • ML theory (20%)
  • • Behavioral (10%)

Difficulty: Very High

Bar: Top 1-5% candidates

Preparation Time: 6-9 months

Indian Unicorns (Flipkart, Swiggy, Razorpay)

Focus Areas:

  • • ML theory (35%)
  • • Coding (25%)
  • • System design (25%)
  • • Projects (15%)

Difficulty: High

Bar: Top 10-15% candidates

Preparation Time: 4-6 months

AI Startups (OpenAI, Anthropic, local AI startups)

Focus Areas:

  • • LLM knowledge (40%)
  • • Coding (30%)
  • • Projects (20%)
  • • Research understanding (10%)

Difficulty: Very High (different skills)

Bar: LLM expertise + can ship code fast

Preparation Time: 3-6 months (if you know LLMs)

→ Learn more about LLM Engineer roles

Service Companies (TCS Digital, Infosys, Wipro)

Focus Areas:

  • • ML basics (40%)
  • • Python (30%)
  • • Projects (20%)
  • • Communication (10%)

Difficulty: Medium

Bar: Top 30-40% candidates

Preparation Time: 3-4 months

The Ultimate Preparation Strategy

Timeline: 4-Month Intensive Prep

Month 1: ML Theory Mastery

Week 1-2: Supervised Learning

  • • Linear/Logistic Regression
  • • Decision Trees, Random Forest
  • • SVM, KNN, Ensemble methods

Week 3-4: Unsupervised Learning

  • • Clustering (K-means, DBSCAN)
  • • PCA, t-SNE
  • • Anomaly detection

Resources: Andrew Ng's ML course, "Hands-On Machine Learning" book, StatQuest (YouTube)

Month 2: Deep Learning & Projects

Week 1-2: Neural Networks

  • • Backpropagation
  • • CNN architectures
  • • RNN/LSTM

Week 3-4: Build Projects

  • • Image classifier
  • • Sentiment analyzer
  • • Time series predictor

Resources: Fast.ai course, CS231n (Stanford)

Month 3: Coding + System Design

Week 1-2: LeetCode

  • • 50 problems (Easy: 20, Medium: 25, Hard: 5)
  • • Focus on arrays, trees, DP

Week 3-4: System Design

  • • Read "Designing ML Systems" (Chip Huyen)
  • • Practice 5 design questions
  • • Draw architectures

Month 4: Company Research + Mock Interviews

Week 1-2: Company Preparation

  • • Research target companies
  • • Understand their ML use cases
  • • Tailor resume for each

Week 3-4: Mock Interviews

  • • 10 mock interviews (Pramp, Interviewing.io)
  • • Get feedback
  • • Improve weak areas

Daily Schedule (Part-Time: 3-4 hours/day)

Weekdays:

  • • 1 hour: ML theory (watch lecture, read book)
  • • 1 hour: Coding practice (LeetCode)
  • • 1 hour: Hands-on project
  • • 30 min: Review & notes

Weekends:

  • • 2 hours: System design practice
  • • 2 hours: Build projects
  • • 1 hour: Mock interviews

Weekly Goals

  • ✓ Complete 10 LeetCode problems
  • ✓ Finish 1 ML topic thoroughly
  • ✓ Make progress on 1 project
  • ✓ 1 system design practice
  • ✓ 1 mock interview (after month 3)

The Behavioral Round (Often Overlooked)

STAR Method for Answering

  • Situation: Set context
  • Task: Your responsibility
  • Action: What you did
  • Result: Outcome (quantify!)

Example Question: "Tell me about a time you improved model performance"

❌ Bad Answer:

"I tried different algorithms and got better accuracy."

✅ Good Answer:

Situation: Our fraud detection model had 85% recall but 30% false positive rate, causing customer complaints.

Task: I was tasked to reduce false positives while maintaining recall.

Action:

  • • Analyzed false positives - found 60% were small transactions from new users
  • • Added features: user age, average transaction size, location consistency
  • • Implemented ensemble (XGBoost + LightGBM) with probability calibration
  • • Created threshold optimization using business cost function

Result:

  • • Reduced false positives from 30% to 12%
  • • Maintained 85% recall
  • • Saved company $500K annually in customer service costs
  • • Model now in production serving 10M daily transactions

Common Behavioral Questions

  • • "Why do you want to work here?"
  • • "Tell me about a challenging project"
  • • "How do you handle disagreement with your team?"
  • • "Tell me about a time you failed"
  • • "Where do you see yourself in 5 years?"

Preparation: Prepare 5-7 stories using STAR method

Salary Negotiation Strategies

The Numbers (India, 2025)

Entry-Level (0-2 years):

  • • Startups: ₹8-15 LPA
  • • Unicorns: ₹12-20 LPA
  • • FAANG: ₹25-35 LPA

Mid-Level (2-5 years):

  • • Startups: ₹15-30 LPA
  • • Unicorns: ₹25-45 LPA
  • • FAANG: ₹40-65 LPA

Senior (5+ years):

  • • Startups: ₹30-60 LPA
  • • Unicorns: ₹45-80 LPA
  • • FAANG: ₹65-120 LPA

Negotiation Tactics

1. Never Give Number First

❌ Bad:

Recruiter: "What's your expected salary?"
You: "₹25 LPA"

✅ Good:

Recruiter: "What's your expected salary?"
You: "I'm more focused on the role and team fit. What's the range for this position?"

2. Use Competing Offers

"I have another offer at ₹40 LPA, but I'm more excited about this role. Can you match or come close?"

3. Negotiate Beyond Base Salary

Components:

  • • Base salary (60-70%)
  • • Bonus (10-15%)
  • • Stock/ESOP (15-25%)
  • • Joining bonus (one-time)
  • • Relocation (if applicable)

Example:
Company offers: ₹30 LPA base
You: "Can we do ₹32 LPA base + ₹3L joining bonus + ₹5L ESOP?"

Real Example: Negotiation That Worked

Initial Offer: ₹35 LPA (₹30L base + ₹5L bonus)

Counter: "Thank you for the offer. I'm excited about the role. Based on my research and competing offers, I was expecting closer to ₹42 LPA. Can we discuss?"

Company Response: ₹38 LPA (₹32L base + ₹4L bonus + ₹2L stocks)

Final Counter: "Can we add a ₹2L joining bonus to help with transition costs?"

Final Offer: ₹40 LPA (₹32L base + ₹4L bonus + ₹2L stocks + ₹2L joining)

Increase: ₹5L (14% more than initial)

Common Mistakes to Avoid

❌ Mistake 1: Over-preparing Theory, Under-preparing Coding

Problem: Can explain algorithms but can't code them

Solution: 60% coding practice, 40% theory

❌ Mistake 2: Not Practicing System Design

Problem: Fail senior rounds

Solution: Practice 10+ system design questions

❌ Mistake 3: Weak Communication

Problem: Know answer but can't explain

Solution: Practice explaining to non-technical friends

❌ Mistake 4: Ignoring Behavioral Round

Problem: Pass technical but fail behavioral

Solution: Prepare 5-7 STAR stories

❌ Mistake 5: Applying Without Preparation

Problem: Burn opportunities at dream companies

Solution: Prepare 3-4 months, then apply

Your Interview Preparation Checklist

3 Months Before

  • ☐ Start LeetCode (10 problems/week)
  • ☐ Review ML theory (1 topic/week)
  • ☐ Build 2 projects
  • ☐ Read system design book

2 Months Before

  • ☐ Complete 80 LeetCode problems
  • ☐ Master all ML algorithms
  • ☐ Practice 5 system design questions
  • ☐ Polish resume

1 Month Before

  • ☐ Start applying
  • ☐ Do 5 mock interviews
  • ☐ Prepare behavioral stories
  • ☐ Research target companies

Interview Week

  • ☐ Review common questions
  • ☐ Rest properly
  • ☐ Prepare questions for interviewer
  • ☐ Be confident!

Success Stories

Story 1: From ₹10 LPA to ₹45 LPA (Amazon)

  • Background: 3 years software engineer
  • Preparation: 5 months (3-4 hours daily)
  • Strategy: Focused on system design + LeetCode
  • Result: ₹45 LPA offer from Amazon
  • Key Takeaway: System design practice made the difference

Story 2: Fresh Graduate → ₹28 LPA (AI Startup)

  • Background: B.Tech graduate
  • Preparation: 8 months (full-time learning)
  • Strategy: Built 10 LLM projects, active on GitHub
  • Result: ₹28 LPA at AI startup
  • Key Takeaway: Strong portfolio > degree

Story 3: Non-CS Background → ₹22 LPA (Unicorn)

  • Background: Mechanical engineer, self-taught
  • Preparation: 12 months (part-time)
  • Strategy: Bootcamp + 15 projects + 200 LeetCode
  • Result: ₹22 LPA at Indian unicorn
  • Key Takeaway: Consistency beats talent

Conclusion: Your Interview Success Formula

The Math:

  • • 4 months preparation
  • • 3-4 hours daily practice
  • • 150 LeetCode problems
  • • 10 system design practices
  • • 5 mock interviews
  • • 3-5 polished projects
  • = ₹25-60 LPA job

The Reality:

  • • 80% of candidates don't prepare properly
  • • 90% give up before 100 applications
  • • 95% don't negotiate salary
  • Be the 5% who does.

Start preparing today. In 4 months, you could be fielding multiple offers.

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Tags: #AIInterviews #MLInterviews #InterviewPrep #FAANG #TechInterviews #SalaryNegotiation #CareerGrowth #AIJobs #CodingInterview #SystemDesign #MachineLearning

Last Updated: December 2025 | Good luck with your interviews!