§12.3 probability. the probability of an event measures the chances of an event occurring. the...

§12.3 Probability

The probability of an event measures the chances of an event occurring.

The probability is always between 0 and 1.

Probability

The probability an event will succeed is

#( )

#

of ways to succeedP success

total of possible outcomes

Probability, not permutation

Example 1:

Suppose you select two letters at random from the word “fragile”. Find each probability.

A) P(2 vowels)

B) P(2 consonants)

C(1 vowel, 1 consonant)

Example #2:There are 10 boys and 12 girls in a class. What is the probability of choosing a group of 5 people with:

A) P(all boys)B) P(2 boys, 3 girls)C) P(all girls)

Example 3:A bag contains 3 red3 red, 4 4 greengreen and 2 blue marbles. If two balls are selected at random, (without (without replacement)replacement) what is the probability of choosing:

a) P(2 red)b) P(1 red and 1 blue)

Example 4:Sam has 4 Jazz CD’s, 3 Rap

CD’s and 1 Classical CD. If she chooses one CD, puts it back and then chooses another CD, What is the probability that she chooses:

a) 1 jazz and 1 jazzb) 1 classical and 1 rap

A deck of Cards Contains:A deck of Cards Contains:

52 Cards

4 suits ♥ ♦ ♠ ♣13 cards of each suitFace cards: Jack, Queen,

King

Hw # 30 Page 700 9-21 odd, 29-31 all, 32, 39-43 all