Question

Suppose that for a certain experiment p​(b​)equals=0.5 and p​(avertical line upper bb​)equals=0.2. find p​(aintersect∩b​).

Answer 1

p(a | b) = p(a ∩ b)/p(b) . . . . . a definition worth remembering
0.2 = p(a ∩ b)/0.5 . . . . . . . . fill in the given values
0.2*0.5 = 0.1 = p(a ∩ b)

p(a ∩ b) = 0.1