Originally Posted by

**rewtuser** Two professors: Prof. Strange and Prof. Boring.

100 published papers. 45% published by Strange. 35% published by Boring. 10% of the papers involve both professors.

Let A denote publication by Strange

Let B denote publication by Boring

P(A)= .45

P(B)= .35

P(A intersect B) = .1

How many of the published papers were authored by:

a.) neither Strange nor Boring?

addition rule: P(A union B)= P(A)+P(B)-P(A intersect B), resulting in

P(A union B) = .7, or 70 papers involved either professor, take the compliment of P(A union B),meaning:

**30 papers have nothing to do with Strange nor Boring.**

Now, where I get confused:

b.) How many published papers were authored by at most one of these two professors?

How would I go about answering this?