Question: In electronics, a wafer is a thin slice of semiconductor material used in the fabrication of integrated circuits and other micro-devices. They are formed of highly pure crystalline material, which is doped (i.e., impurity atoms are added) to modulate its electrical properties. The doping is either n-type or p-type. Moreover, the doping is either light or heavy (one dopant atom per 100 million atoms, or per ten thousand atoms, respectively). The following table shows a batch of 10 wafers broken down into the four categories.
One wafer is selected at random. Let E1 denote the event that the selected wafer is n-type, and E2 the event that the wafer is heavily doped. Find the probabilities P(E1), P(E2), P(E1 ∩ E2), P(E1 ∪ E2), P(E1 - E2), and P((E1 - E2) ∪ (E2 - E1)).