Home › Adventure Map › Statistics_probability › Basic Probability
← Return to Adventure Map

Basic Probability

The Hook

What are the odds?

What is it?

A fraction representing the likelihood of an event occurring: (Part / Whole).

Time Travel (History)

Pascal used this to calculate how to divide the pot of an unfinished gambling game fairly.

Cheat Code

OR means Add (+). AND means Multiply (*).

Practice This Now!

The Field Guide

In Plain English: Probability is just counting. The top number is 'Good Outcomes' (what you want). The bottom number is 'Total Possible Outcomes'. It's always a decimal between 0 and 1.

In The Real World: Insurance. Companies calculate the probability of you crashing your car to set your price.

How To Do It

  1. Count the number of 'Success' outcomes.
  2. Count the 'Total' number of possible outcomes.
  3. Write as a fraction: Success / Total.
  4. Convert to % by multiplying by 100.
⚠

Booby Trap!

The Gambler's Fallacy. Thinking a coin is 'due' to hit Heads after 5 Tails. The coin has no memory. It's always 50%.

Real World Challenge
"A jar has 3 red marbles and 7 blue marbles. What is the probability of picking red?"
The Logic: Successes (Red) = 3. Total Marbles = 10. Probability = 3/10 or 30%.

Training Drills

Coin Flip
Heads: 1/2 Tails: 1/2
Total must sum to 1.