Counting
and Introduction to Probability – Topic 5
Material
to Supplement MTH 110: Prealgebra Online
Probability
is the likelihood that an event will happen.
Probability has values between 0 (absolutely will not happen) to 1
(absolutely will happen). Sometimes
the probability is expressed as a fraction between 0 and 1, sometimes it is
expressed as a percent between 0% and 100%, and when you study probability at a
more advanced level it is expressed as a decimal to three or more places.
But again, between 0 and 1.
You
know if you have a fraction you need a part and a whole (numerator over
denominator). Since a probability
is a fraction you need to know the part you want to consider (called the
successes of an experiment) and the whole (called the sample space or all
possible outcomes of an experiment).
We
will begin by learning how to find sample spaces or finding the number of
outcomes in an experiment.
Sample
Spaces
Activity
1:
This site will both explain what a sample space is and give you several
sample spaces. Be sure you could
find these sample spaces if you were asked to. http://regentsprep.org/Regents/math/sampsp/Lsample.htm
Activity
2:
After you have mastered Activity 1 go to http://regentsprep.org/Regents/math/sampsp/PracSamp.htm
and complete the problems. Be sure
to look at the listing of the sample spaces as well as the number of items in
the sample space. Both are very
important to know.
Activity
3:
In the above activities you have “listed” the sample space.
The tree diagram is another method used to find all the items in a sample
space. Visit http://regentsprep.org/Regents/math/tree/Ltree.htm
for examples. Note:
On the three diagrams you will see some red fractions – these are
probability. Just ignore them –
you do not need to understand what there are or where they came from to
understand the tree diagrams. After
studying this site go to http://regentsprep.org/Regents/math/tree/PracTre.htm
and do the first three examples. You
will need to study probability before doing the rest of the problems.
Activity
4:
Visit http://regentsprep.org/Regents/math/tree/Ttree.htm
to answer the question about whether the order you set up your tree diagram
matters.
Probability
Activity
5:
This site will provide an introduction to probability and some problems
at the end. http://www.mathgoodies.com/lessons/vol6/intro_probability.html
Activity
6:
At this site you can test yourself.
Answers are at the bottom of the site.
Note: This is a pdf file so
you will need to cut the URL and paste it into the address space on your web
browser. If you do not cut and
paste, you may get a virus caution. You
should already have downloaded Adobe Acrobat Reader when you completed the
Activities in Topic 3. Go to http://www.glencoe.com/sec/math/prealg/mathnet/pr01/pdf/0903a.pdf
and check how you are doing.