Sample Space

A theater uses a letter to show which row a seat is in, and a number to show the column the seat is in. If there are rows A-J and numbers 1-20, how many seats are in the theater?

200 seatsHow does this relate to sample space in probability?

Sample Space is the set of all possible outcomes of a situation

If the theater has A-J rows and 1-20 seats, what is the probability you sit in any seat in row D?

Probability of sitting in row D or E?

10

1

200

20

5

1

200

40

200

20

200

20

In Probability:Number of favorable outcomes =

Number of possible outcomes

P(choosing red marble from bag of 5 yellow, 3 black and 4 red)

4/12 = 1/3

1) P(rolling 7 on 2 number cubes)

6,1+5,2+2,5+3,4+4,3+1,6 = 6/36 = 1/6

2) P(flipping coin twice and getting 2 heads)

½ * ½ = ¼

Why do you add versus multiply in probability?

Susan, Joanne, and Dianne are triplets. Susan has red, blue, green and yellow sweaters. Joanne has green, red, purple and white sweaters. Dianne has red, blue, purple, and mauve. They pick sweaters to wear at random.

List all the possible outcomes first.

1) P(each girl chooses different color)21/32

2) P(each girl chooses same color)1/64

3) P( two girls choose same color, and third chooses different color)

21/64

4) P(each girl chooses a red sweater)1/64

Theoretical Probability – what theoretically should happen

A letter is selected at random from letters of FLORIDA. What is probability the letter is an A?• 7 letters to choose from (possible outcomes)• 1 A possible (favorable outcome)• 1/7Complement of event A (not A)?• 7 to choose from (possible outcomes)• 6 not As• 6/7Probabilities of an event and its complement add to 1 or 100%

Theoretical ProbabilityUse the letters MATHEMATICS. Find each

probability.

1) P(M)2/11

2) P(not vowel)7/11

3) P(not E)10/11

4) P(T or S)2/11 + 1/11 = 3/11