probability

Probability Ms. Steele’s Fourth Grade

ClassMay 3rd, 2010

What is probability?

• Probability is defined as the likelihood that an event will occur, expressed as the ratio of the number of favorable outcomes in the set of outcomes divided by the total number of possible outcomes

What does that mean?

• Probability tells you the chances of a certain event, such as getting struck by lightning or choosing a blue cube out of a bag full of cubes.

For example:

You have a bag filled with colored cubes. In this bag you have:• 3 yellow cubes• 4 red cubes• 1 blue• 6 green cubes Out of the cubes in the bag, what are the chances

of us picking a yellow cube? A red cube? A blue cube? Or a green cube?

What happens when we don’t replace the item?

• What do you think happens when you don’t replace the last item you chose?

• What would be the probability of choosing each type of cube?

Let’s see what happens..

This bag is filled with different types of candy.

What are the types of candy we have and how many are there of each?

Our Experiment

We have 7 Twix, 8 Skittles, and 8 Reese’s Peanut Butter Cups. How many do we have in total?

What is the probability of..

• Selecting a Twix out of our bag of candy? (Hint: there are 7 Twix in our bag)

7/23Or

7 out of 23

Let’s See What Happens if We Don’t Replace the Candy!

• What is the probability of the volunteer selecting one type of candy?

• What is the probability of the volunteer selecting two different types of candy?

• What is the probability of the volunteer selecting every other type of candy except for the first one they selected?

Thank you for participating!

Enjoy the candy!