Precalc probability 2014

A. What is the chance that the sun will come up tomorrow? B. What is the chance that, while you are sleeping, your bed will �C. turn to chocolate? D. What is the chance that it will rain today? �E. What is the chance that the temperature will reach at least 70°F �

today? F. What is the chance that you will have homework tomorrow

night?G. Come up with one of your own events.

Algebra 2 Warm up3.11.13

Directions: Place each event on the scale according to how likely it is to happen

Probability

The chance or likelihood of an event happening

A probability is a number between 0 and 1.0 = impossible1 = Certain

Who invented Probability?

PascalFermat

1600’s – Games of Chance

Theoretical vs. Experimental Probability

• Theoretical Probability - What we expect to happen based on mathematics.

• Experimental Probability – What actually does happen

The great number of times you perform an experiment, the closer the 2 become.

How do we calculate Theoretical Probability.

• Probability =

• Ex: Probability of getting HEADS in a coin toss.

Probability of getting the sum of 7 when rolling 2 dice:

Practice1. 2 dice are rolled.

a. Find the probability that the sum of the numbers is 10 b. The sum is at least 10

2. A letter is selected at random from the word TRIANGLE.a. Find the probability of selecting a vowelb. Find the probability of selecting a letter between F and Q.

Compliment

• The probability of an event NOT happening.• Remember the total probabilities add to 1.

Let P(A) = probability of event A

1 - P (A) = probability of event A NOT happening

Examples

2 possible scenarios

• 2 coins are tossed. Find the probability of:– A. Both showing heads– B. Both coins matching– C. There is at least one tails.

Example 2• A stack of 26 cards consists of the hearts and clubs only.

A card is randomly drawn. Find the probability that it is: A. A king B. A diamond C. A club D. A 7 or 8 E. A Red Ace

Example 2• A stack of 26 cards consists of the hearts and clubs only.

A card is randomly drawn. Find the probability that it is: A. A king B. A diamond C. A club D. A 7 or 8 E. A Red Ace

Without replacement.• A bag contains 2 purple, 3 green, and 4 blue marbles. 2 marbles are drawn at random. Find the probability of A. Both being green B. One is Green and one is Blue.