# Thread: Basic Mutually Exclusive Question

1. ## Basic Mutually Exclusive Question

I'm stuck on one of my homework problems.

Let A and B be mutually Exclusive events where P(A)=0.3 and P(B)=0.4

a. Find the Probability that both A and B occur.
b. Find the probability that either of A or b occur.
c. Find the probability that B occurs but A does not occur.
d. Find the probability that neither occurs.

For part a I got 0
For part b I got 0.7

2. ## Re: Basic Mutually Exclusive Question

Originally Posted by reemas
I'm stuck on one of my homework problems.
Let A and B be mutually Exclusive events where P(A)=0.3 and P(B)=0.4
a. Find the Probability that both A and B occur.
b. Find the probability that either of A or b occur.
c. Find the probability that B occurs but A does not occur.
d. Find the probability that neither occurs.
For part a I got 0 CORRECT!
For part b I got 0.7 CORRECT!
c. Find the probability that B occurs but A does not occur.
That is $\mathcal{P}(B\cap A^c)$.
But $B\cap A^c=B$ because they are mutually exclusive.

3. ## Re: Basic Mutually Exclusive Question

Thanks. That's what I thought and wrote down but was unsure.

For part d is the answer 0? Since one has to occur?

4. ## Re: Basic Mutually Exclusive Question

Originally Posted by reemas
For part d is the answer 0? Since one has to occur?
That is incorrect.
Because $A^c\cap B^c=(A\cup B)^c~.$
That is the complement of part b).