# Homework Help: Probability Involving AND and OR

1. May 22, 2012

### Derivator

Hi folks,

1. The problem statement, all variables and given/known data
At Roanoke College it is known that 1/3
of the students live off campus. It is also known that 5/9
of the students are from within the state of Virginia and that 3/4
of the students are from out of state or live on campus. What is the
probability that a student selected at random from Roanoke College is from out
of state and lives on campus?

2. Relevant equations

-

3. The attempt at a solution

It should yield:
P(out off state OR lives on campus) = P(out off state) + P(lives on campus) - P(out off state AND lives on campus)
thus
P(out off state AND lives on campus)
= P(out off state)+P(lives on campus)-P(out off state OR lives on campus)
=(1-5/9)+(1-1/3)-(3/4)
=4/9 + 2/3 - 3/4
=13/36
Is this correct?

-derivator

2. May 22, 2012

### RoshanBBQ

Yes.

3. May 23, 2012

### Derivator

thanks

4. May 23, 2012

### HallsofIvy

The phrase should be "out of state", not "out off state".