How do you find the probability of pulling a blue

marble?A bag is full of 3 blue, 4 green and 2

red marbles.

In this lesson you will learn to find the probability of events with multiple possibilities by combining their probabilities.

Let’s Review

Theoretical Probability:

12 3

45

678

A Common Mistake

Sample space:

A B

CA

C

{A, B, C}

{A, A, B, C, C}

Core Lesson

+ + + + + + + + = 1

1 2 3 4 5 6 7 8 9

Core Lesson

{1, 2, 3, 4, 5, 6}

+ + + + + = 1

What is the probability of rolling a 4 or greater?

P(≥4)=

In this lesson you have learned how to find the probability of

events with multiple possibilities by combining their

probabilities.

Guided Practice

You roll a six-sided die. What is the probability of rolling an odd number?

Extension Activities

Give groups of students bags of marbles and ask them to put however many marbles they want in the bag. Then have the students guess what marbles they will pull out if they perform 25 experiments and replace the marble each time. How do the predictions compare to their actual results?

Extension Activities

Students create their own spinners and then find the theoretical probability of each outcome. Then a partner will experiment with their spinner and compare results to the theoretical probabilities.

Quick Quiz

You roll a six-sided die. What is the probability of rolling a 3 or greater?

Quick Quiz

What is the probability of spinning a 3 or higher on the spinner below?

1 234

42

1 3