Consider randomly selecting a student at a large university. let a be the event that the selected student has a visa card, let b be the analogous event for mastercard, and let c be the event that the selected student has an american express card. suppose that p(a) = 0.6, p(b) = 0.4, and p(a ∩ b) = 0.3, suppose that p(c) = 0.2, p(a ∩ c) = 0.13, p(b ∩ c) = 0.1, and p(a ∩ b ∩ c) = 0.09.