Probability Basics
📋 What it is
Probability of an event = favorable outcomes ÷ total outcomes, a number from 0 (never) to 1 (certain).
🗣️ Coach says
Probability measures how likely something is, as a fraction between 0 and 1. Rolling a 3 on a die is 1 of 6 equally-likely outcomes, so 1/6. Data science lives on probability — it’s how we reason about uncertainty.
🧠 Memory hook
Probability = WANT ÷ TOTAL, always between 0 (impossible) and 1 (certain). 1/2 = a coin flip.
😂 Giggle
What did the mean say to the data set?
"I'm just your average friend!"
😲 Whoa!
A "1 in a million" event still happens to somebody every day in a country of hundreds of millions — rare doesn’t mean never.
✅ Quick check: What is the probability of rolling an even number on a normal 6-sided die?
Say your answer out loud first — then reveal.
1/2 — three evens (2, 4, 6) out of 6 outcomes.
3 favorable ÷ 6 total = 3/6 = 1/2.
🧪 Try it! (2 minutes)
Roll a die 12 times and tally each number. Do they land roughly even (about 2 each)?