This document defines probability and provides examples of calculating probability using fractions, decimals, and percentages. It explains that probability is a measurement between 0 and 1 that indicates the likelihood of an event occurring. Examples are given showing how to convert between fractions, decimals, and percentages in probability calculations. The document also demonstrates calculating probability using examples like dice rolls, spinners, and drawing from jars without replacement to find the probability of different outcomes.

1. By: Christie Potter
BaileyWeaver “88 Kings and Queens” Oct 25, 2009 via Flickr,CreativeCommons Attribution

2. What is a probability?
Three major points
1.An experiment (Situation)
2.An outcome (Result)
3.An event (Single Result)
Probability=
measurement of a single event
occurring

3. • 0=NO chance of the probability
occurring
• In Between = represented with
fractions, decimals, & percent
• 1=the probability WILL occur
0-1 Probability

4. • Percent: 0-100% probability
• Decimal: 0.0-1.0 probability
• Fraction: 0/1 - 1/1 probability
• Each can be interchangeable
Using Fractions,
Decimals, & Percent

5. Example: 20%
• Fraction  20/100 can be SIMPLIFIED to 1/5
• Decimal  20% DIVDED by 100% = .2
Starting At A Percent

6. Example: ¾
• Percent  ¾ is EQUAL to 75/100 or 75%
• Decimal  3 DIVIDED by 4 equals .75
Starting At A Fraction

7. Example: .5
• Percent  .5 MULTIPLIED by 100 = 50%
• Fraction  50/100 can be SIMPLIFIED to
½
Starting At A Decimal

8. # of ways event can occur
P (A) = total # of possible outcomes
Where A = The Event
Probability of an Event

9. • IF P (A) > P (B)
• THEN A is more likely to occur
• IF P(A) = P(B)
• THEN P (AB) are equally likely to occur
Probability A vs. B

10. Dice Example
• Probability (1/6)
- for each number 1-6
• 1 = each number on a die
(1,2,3,4,5,6)
• 6 = total number of sides

11. Continued…
We Can Also Say…
•Probability of EVEN numbers:
•P (3/6) OR  (1/3)
•Probability of ODD numbers:
•P (3/6) OR  (1/3)
Leah Love “Dice Isn’t Just A Game; It’s aWay of Life” Aug 18,
2005 via Flickr,Creative Commons Attribution

12. •P (Yellow) = ¼
•P (Blue) = ¼
•P (Green) = ¼
•P (Red) = ¼
A Spinner Example

13. •Used when drawing from a bag
•Take object out without putting back
•Carton has 12 eggs
•  I take one
• 11 are left
ProbabilityWithout
Replacement

14. • I have 30 pieces
•7 are Red
•23 are Blue
•I’m going to pass them out
Jar of Candy
Ella Novak “Jar of Candy” Jan 5, 2003 via Flickr,Creative
Commons Attribution

15. Creating A ProbabilityTree
Candy
P (Red)
7/30
P (Blue)
23/30
P (Red)
6/29
P (Blue)
23/29
P (Red)
7/29
P (Blue)
22/29

16. •P (Red, Red) : 7/30 MULTIPLY by 6/29
= 42/870
•P (Red, Blue) : 7/30 MULTIPLY by 23/29
= 161/870
•P (Blue, Blue) : 23/30 MULTIPLY by 22/29
= 506/870
•P (Blue, Red) : 23/30 MULTIPLY by 7/29
= 161/870
The Math

17. •Q: Which is MOST likely to occur?
•A: P (Blue, Blue)
•Q: Which is LEAST likely to occur?
•A: P (Red, Red)
•Which are EQUALLY likely to occur?
•A: P (Red, Blue) & P (Blue, Red)
Q & A