Out of 20 components, 3 are defective. Two components are chosen at random from these 20 components. Determine the probability that they will both be defective.
I thought these are two independent events occurring in any order, thus:
P(E1 and E2 in any order) = P(E1 then E2) + P(E2 then E1)
But that doesn't give me the right answer. :(