I was reading this article which has the following question,
Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.
Which is more probable?
Linda is a bank teller.
Linda is a bank teller and is active in the feminist movement.
I chose the second option but according to a set theorem the choice was wrong. Why is not possible that linda can be both a bank teller and feminist? What is the simple explanation to this with example?