Probability: What Chance Do You Have?
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Transcript Probability: What Chance Do You Have?
Probability: What Chance Do
You Have?
Mrs. Gibson
Math 6
PROBABILITY
Definitions
Outcomes
Probability
Complex Probability
Odds
Samples of each
OUTCOMES
For any event or experiment, the end
result is called an outcome.
Probability
Probability is defined as a ratio comparing the
number of favorable or wanted outcomes to the
number of total possible outcomes.
Probability =
Number of wanted outcomes
Number of total possible outcomes
All probabilities are between 0 and 1 inclusive.
Complex Probability
Complex probability deals with multi-step
events. You find the individual
probabilities for each step or part of the
event first, then multiply those
probabilities to find the multi-step
probability.
Odds
The concept of odds are usually included
in the discussion of probability even
though the odds of an outcome are
different from the probability of the same
outcome.
There are two different types of odds:
Odds against an outcome
Odds in favor of an outcome
Both types of odds are defined as a ratio,
just like probability.
Odds against =
Number of unfavorable outcomes
Number of favorable outcomes
Odds in favor of =
Number of favorable outcomes
Number of unfavorable outcomes
There is a direct relationship between the
two types of odds.
Notice that the two types of odds are
reciprocals of each other.
Samples
Outcomes
You roll a die. The outcomes are:
Roll a one
Roll a two
Roll a three
Roll a four
Roll a five
Roll a six
Samples
(Simple) Probability
You use a deck of cards without jokers and
draw a card at random. The probability of
drawing a red card is 26/52 or ½ in lowest
terms.
Samples
Complex Probability
You have a class with 5 boys and 8 girls. You draw a
student at random, and then pick a different student
at random next. The probability of choosing two girls
in a row would be found by multiplying the probability
of picking a girl the first time by the probability of
picking a girl the second time. 5/13 x4/12 = 5/39.
Samples
Odds
If you are rolling a die the odds in favor of
rolling a six is 1 to 5 (1/5) while the odds
against rolling a six is 5 to 1 (5/1).
There are still many more topics in the
field of probability…permutations,
factorials, dependent vs. independent
multi-step events, and on and on.
Let’s go exploring!!!!!!