~ 8.2 ~

Chance Experiments

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Unit 8

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Learning Targets

I can describe the likelihood of events using the words impossible, unlikely, equally likely as not, likely, or certain.
I can tell which event is more likely when the chances of different events are expressed as fractions, decimals, or percentages.

Notes

A chance experiment is something that happens where the outcome is unknown. For example, if we flip a coin, we don’t know if the result will be a head or a tail. An outcome of a chance experiment is something that can happen when you do a chance experiment. For example, when you flip a coin, one possible outcome is that you will get a head. An event is a set of one or more outcomes.

We can describe events using these phrases:

Impossible
Unlikely
Equally likely as not
Likely
Certain

For example, if you flip a coin:

It is impossible that the coin will turn into a bottle of ketchup.
It is unlikely the coin will land on its edge.
It is equally likely as not that you will get a tail.
It is likely that you will get a head or a tail.
It is certain that the coin will land somewhere.

The probability of an event is a measure of the likelihood that an event will occur. We will learn more about probabilities in the lessons to come.

Vocabulary

chance experiment

A chance experiment is something you can do over and over again, and you don’t know what will happen each time.

For example, each time you spin the spinner, it could land on red, yellow, blue, or green.

event

An event is a set of one or more outcomes in a chance experiment. For example, if we roll a number cube, there are six possible outcomes.

Examples of events are “rolling a number less than 3,” “rolling an even number,” or “rolling a 5.”

outcome

An outcome of a chance experiment is one of the things that can happen when you do the experiment. For example, the possible outcomes of tossing a coin are heads and tails.

Activities

2.1 Which is More Likely?

Which is more likely to happen?

When reaching into a dark closet and pulling out one shoe from a pile of 20 pairs of shoes, you pull out a left shoe.
When listening to a playlist—which has 5 songs on it—in shuffle mode, the first song on the playlist plays first.

Remember: The outcomes for the shoes/songs scenarios are not certain. It is possible to do both scenarios, but it isn’t very likely.

2.2 How Likely Is It?

Categories of Likelihood Example

Let’s consider examples about opening a 100 page book...

Impossible: opening the book to page -300
Unlikely: opening the book to exactly page 45
Equally likely as not: opening the book to a page numbered less than 51
Likely: opening the book to a page numbered greater than 10
Certain: opening the book to a page numbered less than 1,000

Label each event with one of these options:

impossible, unlikely, equally likely as not, likely, certain

You will win grand prize in a raffle if you purchased 2 out of the 100 tickets.
You will wait less than 10 minutes before ordering at a fast food restaurant.
You will get an even number when you roll a standard number cube.
A four-year-old child is over 6 feet tall.
No one in your class will be late to class next week.
The next baby born at a hospital will be a boy.
It will snow at our school on July 1.
The sun will set today before 11:00 p.m.
Spinning this spinner will result in green.
Spinning this spinner will result in yellow.

Standard Number Cube

an object that has the numbers 1 through 6 printed on a cube so that each face shows a different number (dice)

2.4 Card Sort: Likelihood

OPEN THE PDF →

You have two sets of cards that describe events.

Order the events of SET 1 from least likely to most likely.
Order the events of SET 2 from least likely to most likely.

7.8.2.4 Activity

Add to Your Notes

What is a chance experiment?

something you can do repeatedly without knowing what is going to happen each time

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