A local zoo imported seven rare birds from a South American country. Suppose that among the seven, three have a fatal disease. As usual, a customs officer must inspect and so he randomnly selects...

Extracted text: A local zoo imported seven rare birds from a South American country. Suppose that among the seven, three have a fatal disease. As usual, a customs officer must inspect and so he randomnly selects three birds and sends them for testing. If we let X denote the number of diseased birds, it can be shown that the probability mass function of X is: if r = 0, 1, 2, 3, px (r) = () 0. otherwise. What is P(1 < x="">< 2)?="" o="" 0.3429="" o="" 0.5143="" o="" 0.6531="" o="" 0.7716="" o="">