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What is Probability?. Probability is the likelihood of something happening.Probability is expressed as a fraction as the number of desired outcomes over the number of possible outcomes.. Probability. The highest probability of an event occurring is:1The lowest probability of an event occurring is:0.
                
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1.    by Trip Lenahan
2007-2008 
 
2. What is Probability? 
Probability is the likelihood of something happening.
Probability is expressed as a fraction as the number of desired outcomes over the number of possible outcomes. 
3. Probability The highest probability of an event occurring is:
1
The lowest probability of an event occurring is:
0 
4. Professions That Use Probability Insurance companies
Professional card players
Casino operators
Athletes
Sports Analysts
Statistics keepers
Secretaries
Accountants
Doctors 
5. Two-Step Procedure   To determine probability, one may use this two-step procedure:
		1. Determine and count all logical 	possibilities
		2. Determine and count all desired 	possibilities or  “winners” 
6. Probability Formula   
The Probability Formulas are as follows:
             p=       number of winners
			    total number of possibilities
OR
             p=        winning region
			        total possible region 
7. Example of Probability #1 
If there are 10 balls (7 red, 3 green) then the likelihood of selecting a red ball on one attempt is ….
				        
	     7        red balls (winners)
	     10        total balls (total possibilities) 
8. Example of Probability #2 Problem: If one of the four points is picked randomly, what is the probability that the point lies on CA?
 
9. Example of Probability #2 (cont) To solve this problem, we first list all
	possibilities
	A		B		C		D
Then, we circle the winners
	A		B		C		D 
10. Example of Probability #2 Solution Therefore the probability of the selected point being on the angle is: 
 Winners     =  3
Possibilities      4 
11. Practice Problem #1 If one of the four angles is selected randomly, what is the probability that the angle is acute? 
12. Example of Probability #3 Problem: If two of the four points are picked at random, what is the probability that both lie on  CA?
 
13. Example of Probability #3 AB	BC	CD	
AC	BD	
AD	
	    
14. More Probability (pg 52 #10) If point B is chosen on AC, what is the probability that -5 < B < 7? 
15. Still more… (pg 52 #11)   The second hand of a clock sweeps continuously around the face of the clock. What is the probability that at any random moment the second hand is between 7 and 12? 
16. Last one… (pg 52 #15)   If a point is chosen at random in rectangle ABCD, what is the probability that:
a. It is in square SQUA? 
17. Last one (really)… (pg 52 #15)   If a point is chosen at random in rectangle ABCD, what is the probability that:
b. It is not in square SQUA?