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PROBABILITY

What do you think the chances are…?

Probability…what is it?

Probability is the chance of an event occurring.

Its value ranges from 0 to 1. 0 means – not going to happen 1 means – always will happen We find probability by measuring what

we want to happen and putting it over the total outcomes that can happen

Example A number cube, which is how dice is

referred to as on the PSSA, is rolled. What is the probability we roll an odd number?

How many odd numbers are on a number cube?

How many total numbers (outcomes) are on a number cube?

P(odd) = We can reduce this fraction

P(odd) =

You try one

A bag of marbles contains 8 red, 5 blue, 1 black, and 2 green marbles. What is the probability of selecting a green marble?A) B)C)D)

What if two or more things need to happen? Find the probability of each individual

event. If they need to happen together, find the

product of the events. Formula: P(event #1) • P(event #2) =

P(both events)

Example

Find the probability of flipping a coin and getting heads while rolling a number greater than 4 on a number cube.

P(heads) = P(greater than 4) = P(heads and greater than 4) =

You try one

Find the probability of spinning a red on the spinner and rolling an even number?

A) B)C)D)