A university in Alabama has 1000 employees. Four hundred of the employees have at least 20 years of experience (event A), 100 are African American (event B), and 300 with a background in Microsoft Office 2003 (event C). Assume A,B,C are independent. What is the probability of finding an employee who meets at least two of the three criteria? Answer is suppose to be .166, but how?

Question

A university in Alabama has 1000 employees.  Four hundred of the employees have at least 20 years of experience (event A), 100 are African American (event B), and 300 with a background in Microsoft Office 2003 (event C). Assume A,B,C are independent.  What is the probability of finding an employee who meets at least two of the three criteria?  Answer is suppose to be .166, but how?

freckles · Answer

@zarkon :)

freckles · Answer

I thought I do P(ABC)+P(AB)+P(AC)+P(BC)
=P(A)P(B)P(C)+P(A)P(B)+P(A)P(C)+P(B)P(C)
but that doesn't work :(

anonymous · Answer

That should work... hmmmm

anonymous · Answer

Try drawing either a Tree Diagram or a Venn Diagram. You've counted some events (like ABC) more than once.

anonymous · Answer

agreed^

freckles · Answer

So how do I draw a venn diagram for independent events?

freckles · Answer

That would be three separate venn diagrams right?

anonymous · Answer

Oops, yes, you're right. What about Tree Diagrams?

freckles · Answer

:( I don't know. I'm not seeing it.

anonymous · Answer

OK. I'll draw the Tree and label it, but you fill in the probabilities (on here or on a sheet of paper). Agreed?

freckles · Answer

Alright!

anonymous · Answer

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