Help Me To:
Eligible Content M3.D.3.1.2
Help Me To:
Determine the likelihood of an event (more/most likely, less/least likely, equally likely, or impossible).
Did You Know?
Many common, everyday events can be classified as certain or impossible based
on prior knowledge. You can
use logical reasoning to predict whether
a mathematical event is certain or impossible.
Look at the chart below.
Probability is a way
of measuring the
Likelihood or Chance that a particular
thing might happen. This happening is called an Event or
Outcome. Some Probabilities can only be measured in
broad terms. An Event that can happen is called a Possibility.
A Probability can range from Definite (Certain) right through to Impossible. |
||
Certain |
The sun will rise tomorrow |
 |
Likely |
I will have three meals today |
 |
Possible |
It will rain tomorrow |
 |
Unlikely |
I will win the Lottery Jackpot |
 |
Impossible |
I can fly to Mars next week |
 |
Check What You Know First
Write if the event is certain, likely, possible, unlikely or impossible.
I will fly to the moon in the space shuttle next week.
I will become an astronaut someday.
I will go to Space Camp tomorrow.
I will study science in school.
I will study about space in school.
Key Vocabulary
An event is a something that happens.
Probability is the chance that an event will or will not happen.
Certain - An event is certain if it will always happen.
Impossible - An event is impossible if it will never happen.
Likely – An event is likely if it has a good chance of happening.
Unlikely - An event is unlikely if it doesn’t have a good chance of happening.
Outcome - a possible result of an experiment
Possible outcome - something that has a chance of happening
Equally likely - having the same chance of happening
Predict - to make a reasonable guess about what will happen
Learn About It Now
An event is something that happens. An event is certain if
it will always happen. For example, it is certain that
you will study
science in school.
An event is impossible if it will never happen. For
example, it is impossible that you will fly to the moon in the space
shuttle
next week.
Events can be either certain or impossible. Then there are events that fall in between.
For example, it is unlikely that you will go to Space Camp
tomorrow, but it is possible that you may go to Space Camp
at some future date or maybe even become an astronaut someday.
However, it is likely that you will study about space in school, if not this year, then at some future grade level.
Let’s explore the likelihood of events further.
When the probability of one event occurring is greater than the probability
of another event occurring, the
first event is more likely to
occur than the second event.
If the probability of an event is greater than all other events, the event is the most likely to occur.
When the probability of one event occurring is less than the probability of
another event occurring, the first event is
less likely to
occur than the second event.
If the probability of an event is less than any other event, the event is the less likely to occur.
When two events have the same probability of occurring, they are equally likely to occur.
Let’s look at an example.
First count the sections for each number.
On the spinner, you should have counted that there are 4 sections with the
number 5. Since there are more 5’s than
any other number, the spinner
is most likely to
land on 5.
There are 3 sections with the number 3 and only 1 section with the number
1. It is more likely that the spinner will
land on the number 3 than on the number 1.
There are 3 sections with the number 3 and there are 4 sections with the number
5. It is less likely that the spinner
will land on the number 3 than on the number 5.
There is only 1 section with the number 1. The spinner is least likely to land on the number 1.
There are 2 sections that occur equally. There are 2 sections with the
number 2 and there are 2 sections
with the number 4. Since these 2 sections occur equally, it is equally
likely that the spinner will land on the number 2 or 4.
What are the chances that the spinner will stop on the number 6? That
would be impossible because there
is no number 6 on the spinner so it will never happen. However, it is certain you
will land on some number with
every spin.
More Practice on Determining the Likelihood of an Event
First count the sections
for each color. Then answer the questions with
the following answers: blue, red, yellow,
green If there is an answer
with two colors separate the 2 words with a comma. Example: (red, blue)
On which section is the spinner least likely to land?
On which 2 sections is the spinner equally likely to land?
On which section is the spinner most likely to land?
On which section is the spinner most likely to land, yellow or green?
On which section is the spinner most likely to land, red or blue?
Websites to Check Out For Extra Practice
Click on this website to see and hear an explanation of certain,
more likely, less likely or impossible outcomes.
When you get on the site, scroll
down to Teaching Model 20.2 and click on that. This is
nice summary of our lesson above. Make sure to turn on your speakers.
http://eduplace.com/math/mw/models/tm_5.html
Click on this website for short games/activities on probability. Then
select the following: Chances Are, Head I Win,
Heads Up Probability,
Lions and Tigers, Me Too Probability, On Stage Probability, Pin the Tail, What
Are My Chances
and What Should I Wear.
http://www.beaconlearningcenter.com/WebLessons/
Click on this website and then click on probability and statistics. There
will be a lot of different interactive activities for
you to choose. Make
sure that you click on "What, Why and How" in order to understand
the purpose of the
activity and how the activity works.
http://www.shodor.org/interactivate/elementary/#pro
More Instruction and Activities on Probability 
http://math.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww-math.bgsu.edu%2F%7Ealbert%2Fm115%2Fprobability%2Foutline.html
http://www.mathgoodies.com/puzzles2004/puzzles/iprobability1.html
http://www.mathgoodies.com/lessons/vol6/intro_probability.html