SECTION 12- PROBABILITY

Question 1

P(A)

Answer 1

• probability of A

Question 2

P(B)

Answer 2

• probability of B

Question 3

P(A’)

Answer 3

• probability of not A

Question 4

P(B’)

Answer 4

• probability of not B

everything outside of B

Question 5

P(A ∩ B)

Answer 5

• intersection of A and B

Question 6

P(A U B)

Answer 6

• probability of A and B

- union (so it is everyone in A and B)

Question 7

P(A’ ∩ B’)

Answer 7

• probability of not A and not B

- where is it both not A or B (outside the circles)

Question 8

P(A’ ∩ B)

Answer 8

• probability of not A and B

- B not including intersection

Question 9

P(A ∩ B’)

Answer 9

• probability of not B and intersection

- A not including intersection

Question 10

P(A’ U B’)

Answer 10

• union of not A and not B

- all added up except the intersection

Question 11

P(A U B’)

Answer 11

union of A and not B

- includes A and intersection and outside of venn diagrams

Question 12

P(A’ U B)

Answer 12

• union of not A and B

- includes B and intersection and outside of venn diagrams

Question 13

independent events formula

- P( A ∩ B)

Answer 13

P( A ∩ B) = P(A) x P(B)

Question 14

probability of mutually exclusive events

P(A ∩ B)

Answer 14

P(A ∩ B) = {0}

- there’s no intersection and no chance of them happening at the same time (separate venn diagrams)

Question 15

what does it mean if two events are independent

Answer 15

• the outcome of one event doesn’t affect whether or not the other event occurs e.g. rolling a 3, then a 2 on a dice

Question 16

what is an empty set

Answer 16

when two events are mutually exclusive

Question 17

what happens when two events are NOT independent

Answer 17

• the outcome of one event is affected by the outcome of the other e.g. probability you receive an A on your stats. test may change depending on if you did all your hw

Question 18

what does P(A|B) denote

Answer 18

• probability event A occurs given that event B has already occurred
• but if A and B are independent P(A|B) = P(A) since occurrence of B doesn’t affect A

Question 19

conditional probability formaula

Answer 19

P(A|B) = P( A ∩ B) / P (B)

Question 20

formula for finding relating the intersection to the union

Answer 20

P( A U B ) = P(A) + P(B) - P(A ∩ B)

Question 21

what can be used to calculate conditional probability

Answer 21

tree diagrams

Question 22

probability of an event formula

Answer 22

no. of possible outcomes in the event/ total no. of possible outcomes