What does A 3 B mean Consider a family with a mother, father, and two children Let A 1 mother has influenza , A 2 father has influenza , A 3 first child has influenza , A 4 second child has influenza , B at least one child has influenza , C at least one parent has influenza , and D at least one per...

What does A 3 B mean? Consider a family with a mother, father, and two children.

Question:

What does A₃ ∩ B mean?

Consider a family with a mother, father, and two children. Let A₁ = {mother has influenza}, A₂ = {father has influenza}, A₃ = {first child has influenza}, A₄ = {second child has influenza}, B = {at least one child has influenza}, C = {at least one parent has influenza}, and D = {at least one person in the family has influenza}.