Probability: What Chance Do You Have? Mrs. Gibson Math 6

PROBABILITY Definitions Samples of each 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 = All probabilities are between 0 and 1 inclusive. Number of wanted outcomes Number of total possible outcomes

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 = Odds in favor of = Number of unfavorable outcomes Number of favorable outcomes 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!!!!!!