“The probable is what usually happens.”    Aristotle

The probability of an event is a measure of the likelihood that the event will occur.
The probability of any event can range from 0 to 1.

Probability of an event


Predict & Display Data

Probability – Sample Space

Probability Help,   

Probability 2 Help



PR09      Counting

PR10      Probability with a Single Die

PR11      Rolling a single die

PR12      Picking numbers out of a hat

PR13      Probability of picking a marble from a bag_1

PR14      Probability of picking a marble from a bag_2

PR15      On the spinner, what is the probability of …

PR16      Probability With a 10-section spinner

PR17      Probability of picking a tile from a bag.


Finding the Probability of Independent Events

(Sample space UNCHANGED)

If A and B are independent events, then

P(A and B) = P(A)•P(B)


Dependent Events Help,  

Tree Diagram Help






Finding the Probability of Dependent Events  

 (Sample space DECREASES)

If A and B are dependent events, then

P(A and B) = P(A) • P(B given A)



PR19      2Dice

PR21      2Marbles

PR22      2Roses

PR23      2Tiles

PR25      2Bills


Probability – Counting Principle Probability – Independent Event Probability Application

Theoretical probability

Theoretical Probability is determined through reasoning (the ratio of the number of favorable outcomes to the number of possible outcomes).





Experimental probability

Experimental probability is found by repeating an experiment and observing the outcomes.





A monkey is sitting by and hitting 4 keys randomly. Suppose that the monkey is answering a multiple choice MATH STAAR TEST. There are 56 questions and each question has 4 options. Find the experimental probability

PR20      Coin&Die

PR24      3Coins


Probability Writing

Probability rules