Section 2.5: Negative Binomial Distribution

Geometric and waiting for r successes

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Waiting for Success

🎯 A Different Question

In the binomial distribution, we asked: "In n trials, how many successes?"

Now we flip the question: "How many trials until we get r successes?"

Real-World Examples

🎰

How many slot machine pulls until you win?

📞

How many calls until you reach a live person?

🏀

How many free throws until you make 10?

🔍

How many items to inspect until you find 3 defects?

Key Difference from Binomial: Here the number of trials X is random, and we're counting trials (not successes). We keep going until we hit our target!