Odds
What are the odds to win?
Odds are written as a Ratio
Part : Part
Wins : Losses
# of favorable outcomes: # of unfavorable outcomes
what are the odds?
How likely it is that something will happen.
To state the odds, we use a percent or a ratio
( part : part)
0
½
1
Probability
Certain not
to happen
Equally likely to
happen or not to happen
Certain to
happen
Chance
0%
50 %
50:50
100%
Odds versus Probability

The ratio of odds gives 2 complementary
events
 If event A is the favorable outcome
(example: roll a 2 or a 4)
 Event A’ (not A) is the non-favorable
Outcome ( roll a 1,3,5,or 6)
Odds
A : A’ (2:4)
Probability
A / (A + A’)
( 2/6)
Examples
Odds
Probability
2:1
2/3
1:5
1/6
6:3
6/9
1:1
1/2
What are the odds?
1 2
4 3
1. What are the odds of spinning a
number greater than 1?
4 1
2
3
5
2. What are the odds of spinning a
4?
3. What are the odds that the spinner
will stop on an odd number?
4. What are the odds of rolling an even
number with one toss of on number cube?
Playing the odds
We write the odds as a fraction
# of favorable outcomes
# of unfavorable outcomes
Playing the odds
# of favorable outcomes
# of unfavorable outcomes
OR
WINS
LOSSES
WE CREATE AN EQUALITY
BET TO WIN
WINS
LOSSES
= $ BET
$ EARNED
Example: The odds that Pete’s team will win is 4:3
I bet $5 to win
4 = 5
3 X
4X = 15
X = 3.75
I WIN $3.75 AND I GET MY $5 BACK
EXAMPLES
BET TO LOSE
WINS
=
LOSSES
$ EARNED
$ BET
Example: The odds that Pete’s team will win is 4:3
I bet $5 to lose
4 = X
3 5
20 = 3X
X = $6.67
I WIN $6.67 AND I GET MY $5 BACK