statistics
posted by Katia .
A group of 50 teachers and school administrators attended a convention. If any two persons are picked at random, at least one of the two would be a teacher. From this information, what percentage of the people at the convention were teachers?
Could someone help me start this, or go in the right direction? Or show me another example. I don't know where to start.
Thank you

If we have 1000 people, of which exactly two are MEN. Can we claim:
"If any two persons are picked at random, at least one of the two would be a woman."
What does that tell you?
Now back to the above problem:
"If any two persons are picked at random, at least one of the two would be a teacher."
From this information, how many people are NOT teachers?