Probability

Question 1

What does mutually exclusive mean?

Answer 1

Events can’t happen at the same time

Question 2

What does the P(A’) mean?

Answer 2

The probability of A not happening

Also known as the complement of the event A

Question 3

What is the addition law of probability?

Answer 3

P(A u B) = P(A) + P(B) - P(A n B)

Question 4

If events A and B are mutually exclusive what does the probability of A and B equal?

Answer 4

P(A n B) = 0

Question 5

What is the addition law of probability if events A and B are mutually exclusive?

Answer 5

P(A u B) = P(A) + P(B)

Because the -P(A n B) cancels out as it equals 0

Question 6

How can you show that events A and B are not mutually exclusive?

Answer 6

By showing:

P(A n B) does not equal 0

OR

P(A u B) does not equal P(A) + P(B)

Question 7

What do you do if it is AND ?

Answer 7

Multiply

Question 8

What do you do if it is OR?

Answer 8

Add

Question 9

What is the equation if A and B are independent?

Answer 9

P(A n B)= P(A) x P(B)

Question 10

What is useful to know for discrete probability disbributions?

Answer 10

The sum of p(x=x) = 1

Question 11

What makes a probability conditional?

Answer 11

If it depends on what has already happened

E.g. P(B/A) means the probability of B if event A has happened

Question 12

What is the multiplication law

Conditional probability

Answer 12

P(A n B) = P(A) x P(B/A)

Question 13

How can you test if A and B are independent?

Answer 13

Check if:
P(A/B)=P(A)
or
P(B/A)=P(B)
or
P(A n B) = P(A) x P(B)