Probablity Formulae

Question 1

For INDEPENDENT events, what is the probability of (A and B) ?

Answer 1

P(A and B) = p(A) x p(B)

Question 2

For non-mutually exclusive events, which formula can you use ?

(It’s given on the formula sheet)

Answer 2

P(A) + p(B) - p(AnB) = p(AuB)

Question 3

For dependent events, what is the probability of (A given B)

Answer 3

P(AnB)/p(B)

Question 4

For independent events, what is the probability of A given B

Answer 4

It’s just equal to the probability of A on it’s own, as the events are independent

Question 5

For mutually exclusive events, what is the probability of A and B?

Answer 5

0.

This means to find p(AuB) you just add the probability of A and probability of B together

Question 6

What are mutually exclusive events?

Answer 6

Events which can’t both happen at the same time

For example you can’t simultaneously get a head and a tail when you flip a coin.